# What is Change in momentum: Definition and 73 Discussions

In classical mechanics, impulse (symbolized by J or Imp) is the integral of a force, F, over the time interval, t, for which it acts. Since force is a vector quantity, impulse is also a vector quantity. Impulse applied to an object produces an equivalent vector change in its linear momentum, also in the resultant direction. The SI unit of impulse is the newton second (N⋅s), and the dimensionally equivalent unit of momentum is the kilogram meter per second (kg⋅m/s). The corresponding English engineering unit is the pound-second (lbf⋅s), and in the British Gravitational System, the unit is the slug-foot per second (slug⋅ft/s).
A resultant force causes acceleration and a change in the velocity of the body for as long as it acts. A resultant force applied over a longer time therefore produces a bigger change in linear momentum than the same force applied briefly: the change in momentum is equal to the product of the average force and duration. Conversely, a small force applied for a long time produces the same change in momentum—the same impulse—as a larger force applied briefly.

J
=

F

average

(

t

2

t

1

)

{\displaystyle J=F_{\text{average}}(t_{2}-t_{1})}
The impulse is the integral of the resultant force (F) with respect to time:

J
=

F

d

t

{\displaystyle J=\int F\,\mathrm {d} t}

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1. ### Write a realistic word problem for which this is the correct equation

So far for the word problem I have: A 100 g particle, traveling at 40 m/s, collides inelastically with another 100g particle traveling towards it at 30 m/s. Now from the equation provided we need the question to ask us to find delta t, and that's simple enough but I'm not sure what that 1/2 is...
2. ### Weight of gold chain when dropped on a weighing scale

The force exerted downwards on the scale by the chain when it is kept on it would be Fg= Mg =λLg where λ is the linear mass density However when the chain is dropped onto the scale it exerts an additional force due to its change in momentum The force exerted by each part of the chain would...
3. ### Force and change in momentum in an inelastic/elastic collision

Question 1: Since Force=Change in momentum = ∆P / ∆t = mv / t Momentum of the water coming out=mv mv=ρVv=ρAv Force d/dt (ρAv2t)=ρAv^2 Force = 1000*40*30ms^2 Force = 3.6*10^7 N Question 2: This is where I am confused because I understand in an elastic collision total kinetic energy and...
4. ### Finding the correct change of momentum in this system,

I tried out the F=Δp/Δt equation and i came up with a change of momentum of the box-bullet fusion (M+m)V-0, but the textbook says otherwise (using a change of momentum of JUST the box itself, excluding the bullet). According to the textbook, the correct change is MV-0, without the added mass of...
5. ### Change in momentum when given the speed (not the velocity).

1. The problem statement. A tennis ball of mass m moving horizontally with speed u strikes a vertical tennis racket. The ball bounces back with horizontal speed v. Homework Equations p = mv The Attempt at a Solution My answer was m(v-u), meaning the final momentum (mv) subtracted from the...
6. ### Change in Momentum of a Hockey Puck

Homework Statement A hockey player hits a slap shot, exerting a constant force on a 3.06 kg puck for 0.06 seconds. What is the change in momentum of the puck? Homework Equations Impulse = Mass x (Change in velocity) = Force x time (I think that’s all needed? Most likely missing one.) The...
7. ### Change in momentum for a satellite in circular orbit

Homework Statement A satellite is in a circular orbit passing over the North and South geographical poles as it orbits the Earth. It has a mass of 2200kg and its orbit height is 870km above the Earth's surface. What is the change in momentum of the satellite from when it passes over the...
8. ### What is the magnitude of the girl's change in momentum?

Homework Statement A 50-kg ice skater moves across the ice at a constant speed of 2.0 m/s. She is caught by her79-kg partner, and then the pair continues to glide together. He is at rest when he catches her, and immediately afterward they both coast. Part A) What is their velocity just after...
9. ### Magnitude of the change in momentum equation

Homework Statement A single gas molecule of inertia m is trapped in a box and travels back and forth with constant speed v between opposite walls A and B a distance l apart. At each collision with a wall, the molecule reverses direction without changing speed. Write algebraic expressions for...
10. ### Change in Momentum of shopping cart

Homework Statement A 12kg shopping cart rolls due south at 1.5m/s. After striking the bumper of a car, it travels at 0.80m/s at 30. degrees E of South. What is the magnitude and direction of the change in momentum sustained by the shopping cart? Homework Equations p = mv The Attempt at a...
11. ### Change in Momentum using Vectors

Homework Statement A force F = (2ti + 3t^2j) N acts on an object moving in the xy plane. Find the magnitude of change in momentum of the object in time interval t=0 to t=2 (The bold ones are vectors) Homework Equations Ft=change in momentum The Attempt at a Solution magnitude of F = (4t^2 +...
12. ### Change in momentum, impulse force calculations

Homework Statement A 178.0g ball is dropped from a height of 2.99m, bounces on a hard floor, and rebounds to a height of 1.36m. The impulse received from the floor is shown below. (Is a picture of a graph, Y-axis is force, X-axis is time. No numbers are labelled and is simply a line starting...
13. ### Impulse. Change in Momentum vs Ft

My book states that impulse = Ft = mv_f - mv_i But it doesn't make sense to me because what if a Force of 5N is applied to an object for 10 seconds? Then I = Ft = 5N(10s) = 50 Ns. So if I apply 5N to an object with a friction force of 5N for 10s so that the object is traveling at a constant...
14. ### Finding change in momentum in 2-dimensions.

To find the momentum change for an object in 2 dimensions do I find the initial momentum in both the x & y direction then apply the Pythagorean theorem, and then do the same for the final momentum and then find the difference between the two?
15. ### How is the Barrel Length of a Human Cannon Calculated?

Human cannonballs have been a part of circuses for years. A human cannonball with a mass of 70kg experiences an impulse of 4.0 x 10^3 N•s for 0.35 s. a) Calculate the force acting on the human cannonball. F=(J)/(Δt) =(4000 N•s)/(0.35s) =11428.5 N =1.14 x 10^4 N b)How long was the barrel of...
16. ### Momentum: Jumping on a trampoline

Homework Statement A gymnast of mass 40kg is practising on a trampoline. The gymnast lands with a speed of 6.3m/s. The gymnast rebounds with a speed of 5.7m/s. a) Calculate the change in momentum of the gymnast b) The gymnast was in contact with the trampoline for 0.50s. Calculate the...
17. ### Conservation of Momentum of a ball

Homework Statement A ball is thrown against a fixed wall where it bounces elastically. The mass of the ball is M and the velocity just before it hits the wall is U. Ignore the force of gravity in this question. a) Does the Principle of Conservation of Momentum apply to this situation? b) Obtain...
18. ### How Do You Calculate Impulse and Force in a Racquetball Collision?

Question A 0.0420-kg hollow racquetball with an initial speed of 12.0 m/s collides with a backboard. It rebounds with a speed of 6.0 m/s. a. Calculate the total impulse on the ball. b. If the contact time lasts for 0.040 s, calculate the average force on the ball. What I did on the test...
19. ### Why is the change in momentum of a crystal include reciprocal lattice vectors?

So i don't really understand why the change in momentum of a crystal involves a reciprocal lattice vector. Surely it is just the change in momentum due to the change in the number and frequency of the phonons before and after whatever event/scattering/collision takes place. Can somebody please...
20. ### How to find the change in momentum

Homework Statement a shunting locomotive strikes a wagon of mass 8t and sets it in motion with an initial speed of 3.6m/s.The wagon travels freely along a level track against a track resistance of 58N/t for 12s.determine; a.the frictional resistance(average force) b.the reduced velocity...
21. ### Change in momentum of different masses

Homework Statement How is change in momentum related to mass? Will the change in momentum for a mass of 4m being pushed with constant force be same as the change in momentum for a mass of m being pushed with same force?Homework Equations The Attempt at a Solution I know Change of momentum (i.e...
22. ### Change in momentum after hitting a wall

Homework Statement 32) The change in momentum, in kg m/s, that occurs when a 1.0 kg ball traveling at 4.0 m/s strikes a wall and bounces back at 2.0 m/s is A) 2. B) 4. C) 6. D) 8. Answer: C Homework Equations Momentum==Mass*Velocity The Attempt at a Solution I get...
23. ### Change in momentum when a body is thrown up and falls back down.

Say, a body of mass 'm' is thrown at a certain angle with the vertical with certain initial velocity 'u'. The initial momentum of this object is mu. Am I right to say that if it spent 't' seconds in flight and came back, its final velocity will still be 'u'? And the change in momentum will be...
24. ### Change in Momentum of probe Problem

Homework Statement In July 2005, NASA's "Deep Impact" mission crashed a 372-kg probe directly onto the surface of the comet Tempel 1, hitting the surface at 37000 km/h. The original speed of the comet at that time was about 40000 km/h, and its mass was estimated to be in the range (0.10-2.5)...
25. ### Finding acceleration during a change in momentum

Homework Statement A block of mass of 60kg is at rest on a smooth horizontal surface and is then pushed with a constant force of 126N for 10 seconds. Ignoring friction and air resistance; A. calculate the acceleration of the block during the 10 seconds B. calculate the velocity after 10...
26. ### Calculate Change in Momentum of 4.8 kg Mass Launched at 55°

Homework Statement An object of mass 4.8 kg is projected into the air at a 55° angle. It hits the ground 3.6 s later. What is the magnitude of its change in momentum while it is in the air? Ignore air resistance Homework Equations J=p =sumF Δt=mΔv The Attempt at a Solution mvsine(theta)...
27. ### Change in Momentum: Truck v Volkswagen

Homework Statement A truck and a volkswagon have a head on collision. Which vehicle experiences the greater change in momentum? ( Hint: they both experience the same force in the same time.) a. we need more information to determine this b. the truck c. none they experience the same change on...
28. ### Perpendicular Forces and Change in Momentum

Okay, I feel like I am just missing something that should be very easy to see, but I can't seem to wrap my head around this concept. Can anyone explain to me why a force perpendicular to the momentum only changes the direction of the momentum and not the magnitude? By my logic, if...
29. ### Change in momentum of baseball being struck

Homework Statement A 0.33 kg softball has a velocity of 14 m/s at an angle of 50° below the horizontal just before making contact with the bat. What is the magnitude of the change in momentum of the ball while it is in contact with the bat if the ball leaves the bat with a velocity of (a) 15...
30. ### Newton's logic behind taking force as change in momentum w.r.t time?

why Newton had taken force as change in momentum per time? i mean i need to get physical interpretation?what is this force actually? also help me to get an idea about energy in sense(core concept)? not with some equations? i see these equations every time?but didn't know meanining? somebody...
31. ### How Do You Calculate the Change in Momentum for Colliding Masses?

Homework Statement A mass(1) of 10000kg with a velocity 30m/s west collides with another mass(2) of 1200kg with a velocity 20m/s north. After the collision the two masses stick together. Determine the change in momentum of mass(2) before and after the collision. Homework Equations General...
32. ### The law of conservation of momentum and change in momentum

If an object with mass m kg moves towards a wall with velocity u m/s, collides elastically with the wall and finally moves with a velocity –u m/s, then according to the equation of conservation of momentum: mu=-mu where the final momentum of the wall is negligible. This equation does not seem to...
33. ### Simple change in momentum problem

Homework Statement What is the rate of change of momentum when a constant 4N force acts on a mass of 2Kg for 2 seconds ? Homework Equations change in momentum = impulse produced (on the 2Kg mass) by the force ie f*t=δP The Attempt at a Solution i used the above equation to first...
34. ### Momentum Change of Colliding Balls: A Physics Problem

ok so my physics textbooks crap, it explains something in a tiny paragraph without any examples (I'm getting new ones). I have this question I'm stuck on. There is 2 balls that both have the mass of 1.5kg, one is not moving and one is moving at 4m/s - so ball A is about to collide with ball B...
35. ### Force and Change in Momentum

Homework Statement A net external force acts on an object of mass m. Is this information sufficient to conclude that (i) the velocity of the object changes? (ii) the kinetic energy of the object changes? (iii) the speed of'the object changes? Explain your answers in each case.Homework...
36. ### Change in momentum problem. BASIC, IMPORTANT, but i don not know help?

Homework Statement A 0.2 baseball if pitched with a velocity of 40 m/s and is then batted to the pitcher with a velocity of 60 m/s. What is the magnitude of change in the ball’s momentum? A. 4 kg*m/s B. 8 kg*m/s C. 2 kg*m/s D. 20 kg*m/s Homework Equations change in momentum =...
37. ### Change in Momentum: Particle Moves Diametrically Opposite

what will be the change in momentum if a particle moves from one point to its diametrically opposite.
38. ### Ball dropped from heigh and bounces to height, change in momentum?

A bouncy ball of mass 85.3 grams is dropped from a height of 13.17 meters. It rebound to a height of 5.12 meters. What was the change in momentum (in kgm/s) of the bouncy ball?
39. ### Finding angle of change in momentum vector

Homework Statement A billiard ball of mass m = 0.250 kg hits the cushion of a billiard table at an angle of θ1 = 55.8° at a speed of v1 = 27.2 m/s. It bounces off at an angle of θ2 = 71.0° and a speed of v2 = 10.0 m/s. (a) What is the magnitude of the change in momentum of the billiard...
40. ### Kg m/s Change in Momentum of Trolley

Homework Statement A 2.4kg cart is moving with a constant speed of 2m/s along a smooth horizontal plane when a 1.5kg object is dropped vertically onto it. What is the change in momentum of the trolley? Homework Equations p=mv \Deltap=p final - p initial The Attempt at a Solution...
41. ### Calculate Change in Momentum of 20kg Box

[b]1. A 20kg box traveling at 10m/s is pushed with 48N of force for 12 seconds. What is the change in momentum? [b]3. How would you find the change with this? * I know the momentum of the ball initially is 200.
42. ### Impulse & Change in Momentum: 0.5kg Object Dropping 3m

Homework Statement A 0.5 kg object drops from rest from a 3m high point. On bouncing from Earth it rises to a height of 2m. The collision with Earth lasts for about 10^-4 seconds. i) What is the impulse received by the object? ii)Considering that there is a gravitational force present, Can you...
43. ### Change in momentum and change in Kinetic energy

Homework Statement A particle of mass m is thrown vertically upwards with initial speed v. When the particle returns to it starting point, what are the changes in momentum and kinetic energy of the particle. Homework Equations P=mv KE=1/2mv2 The Attempt at a Solution...
44. ### Calculate Change in Momentum of 65kg Runner After Half Revolution

A runner of mass 65kg is running around a circular track at 5m/s. What is the magnitude of the change in his momentum from start to end after half a revolution? My answer if 650Ns, but the answer is written as 625Ns.
45. ### How Does Momentum Change When a Ball Bounces Off a Wall?

1. Homework Statement A ball is rolled into a wall and bounces back at the same speed, the change in momentum is? 2. Homework Equations Ein = Eout 3. The Attempt at a Solution I thought it was m(v) but I got it wrong (doing test corrections ATM) Note I'm having trouble editing...
46. ### What is the difference between momentum and kinetic energy?

Hello! yes is from Sweden and my English is not good, but will try to do as best as possible. My question is: why can not consider the momentum as the acceleration energy? I know that: Impulse is change in momentum which is not the same as energy Impulse can be expressed either as F *...
47. ### Calculate Change in Momentum of Billiard Ball | CaptFormal

Homework Statement A billiard ball of mass m = 0.15 kg strikes the cushion of a billiard table at θ1 = 48° and a speed v1 = 21 m/s. It bounces off at an angle of θ2 = 670 and a velocity of v2 = 16 m/s. What is the magnitude of its change in momentum (in kg·m/s)...
48. ### Calculating Change in Momentum of a Softball After Bat Contact

Homework Statement Pitcher pitches a .30 kg softball has velocity 14 m/s at an angle of 36 degrees below the horizon just before the bat contacts the ball. What is the magnitude of change in momentum if the ball leaves the bat with a velocity of 23 m/s, vertically downward. Homework...
49. ### Collisions and Change in Momentum

Homework Statement A ball of mass 4.7 kg moving with speed of 1.9 m/s in the x-direction hits a wall and bounces back with the same speed in the -x-direction. What is the change of momentum of the ball? And in what direction? Homework Equations p=mv The Attempt at a Solution...
50. ### Calculate Change in Momentum of Mass m Launched at 45° Angle

Homework Statement An object of mass m is launched at speed v from point P on horizontal ground at an angle of elevation of 45 degrees, as shown in the picture. When the object reaches point Q the magnitude of the change in momentum of the object is ? Homework Equations Change in...