Momentum Change & Collision Questions: Answered

  • Thread starter Thread starter ebayunderground
  • Start date Start date
AI Thread Summary
The discussion focuses on various physics problems related to momentum change and collisions. Participants analyze a baseball's momentum change when pitched and batted back, calculating it to be 8.0 kg-m/s. Another problem involves a spring-loaded gun on an air puck, where the bullet's speed is determined to be 12.0 m/s. A scenario with three satellites emphasizes that while they may receive different impulses, they do not always receive equal impulses. Lastly, the final velocity of a 20-kg object after an elastic collision with a 10-kg object is explored, highlighting the importance of momentum conservation principles. Understanding these concepts is crucial for solving momentum-related problems effectively.
ebayunderground
Messages
2
Reaction score
0
1 Jerome pitches a baseball of mass 0.20 kg. The ball arrives at home plate with a speed of 40 m/s and is batted straight back to Jerome with a return speed of 60 m/s. What is the magnitude of change in the ball's momentum?

A 4.0 kg-m/s
B 8.0 kg-m/s
C 18 kg-m/s
D 20 kg-m/s


2 A miniature spring-loaded, radio-controlled gun is mounted on an air puck. The gun's bullet has a mass of 5.00 g, and the gun and puck have a combined mass of 120 g. With the system initially at rest, the radio controlled trigger releases the bullet causing the puck and empty gun to move with a speed of 0.500 m/s. What is the bullet's speed?

A 4.80 m/s
B 11.5 m/s
C 48.0 m/s
D 12.0 m/s


3 Three satellites are launched into space connected together. Once in deep space, an explosive charge separates the three satellites and they move apart. The satellites each have different masses with m1 < m2 < m3. Which of the following statements is always true?

A The one with mass m1 receives the greatest impulse.
B The one with mass m3 receives the greatest impulse.
C They all must receive equal impulses.
D Although one or more of the above statements could be true in special cases, they are not always true.


4 A 20-kg object sitting at rest is struck elastically in a head-on collision with a 10-kg object initially moving at +3.0 m/s. Find the final velocity of the 20-kg object after the collision.

A -1.0 m/s
B -2.0 m/s
C +1.5 m/s
D +2.0 m/s
 
Last edited:
Physics news on Phys.org
Seems like straightforward change in momentum/conservation of momentum problems. What are you having trouble with.
 
I missed the class and don't know how to set it up so if you could show me how to set it up and the answer i'll try it and see if i get it right thanks
 
1) If you know the definition of momentum, then you'll know how to define a change in momentum, too.

2) Use the fact that momentum is conserved.

3) Start off with the definition of impulse.

4) What is conserved in an ellastic collision?
 
TL;DR Summary: I came across this question from a Sri Lankan A-level textbook. Question - An ice cube with a length of 10 cm is immersed in water at 0 °C. An observer observes the ice cube from the water, and it seems to be 7.75 cm long. If the refractive index of water is 4/3, find the height of the ice cube immersed in the water. I could not understand how the apparent height of the ice cube in the water depends on the height of the ice cube immersed in the water. Does anyone have an...
Thread 'Variable mass system : water sprayed into a moving container'
Starting with the mass considerations #m(t)# is mass of water #M_{c}# mass of container and #M(t)# mass of total system $$M(t) = M_{C} + m(t)$$ $$\Rightarrow \frac{dM(t)}{dt} = \frac{dm(t)}{dt}$$ $$P_i = Mv + u \, dm$$ $$P_f = (M + dm)(v + dv)$$ $$\Delta P = M \, dv + (v - u) \, dm$$ $$F = \frac{dP}{dt} = M \frac{dv}{dt} + (v - u) \frac{dm}{dt}$$ $$F = u \frac{dm}{dt} = \rho A u^2$$ from conservation of momentum , the cannon recoils with the same force which it applies. $$\quad \frac{dm}{dt}...
Back
Top