Average force Definition and 178 Threads

What have mistakes/wrong assumption have I made in solving this question? I tried to solve the problem this way N.B. I assume that the j hat direction is up.

I've gone about getting the arclength S = 1.103m The formula for average force is F = m * (Vf – Vi) / t I know the mass and the initial velocity, but I don't know where arclength comes into play. I'm assuming Vf and T is referring to the moment that the ball leaves the pitchers hand, but I...

APPROACH 1 (correct): Height above ground = 3 - (v+u)/2 * t = 3 - 18.263/2 * 0.25 = 0.717 m ----------------------------------------------------- APPROACH 2 (incorrect): Let d be the height from the ground when he is stopped by the cushion. PE loss = Work done against motion by cushion mgh =...

A gun fires 6 bullets per second into a target. The mass of each bullet is 3g & the speed of 500 m/s. Find the average force required to hold the gun in position.

I first wrote down that 55% = Eout/Ein I also know that W = (Facos20)(4) and I substitute it into the first equation 55% = Eout/[(Facos20)(4)] But I'm missing two variables here. Did i forget something or is the question missing some information?

used a) change in momentum / time, time from from kinematics equation d = vi+vf/2 *t ... 0.1 = 300*t =3.33*10^-4 then 600/0.00333 = 1.8*10 ^5 how to proceed?

Homework Statement [/B] Ball with a mass of 0.1 kg travels at a speed of 10 m /s to the boy. Boy kicks the ball with foot so that it bounces back at an angle of 30 degrees with respect to the horizontal floor. The ball falls back to the ground 20 meters from the boy. With what average force...

Homework Statement The average force needed to throw a baseball 90mph. I tried to find the force at 90mph on release and 90mph at the plate and got two wildly different answers and it seems off that they vary soo much. Homework Equations · Velocity- 90 mph or 40.23 m/s measured at...

Homework Statement An athlete on a sled is moving with a speed of 3m/s across a pond with ice. If the total mass of the sled-athlete system is 95 kg, what magnitude of force is required to bring the sled to rest in 15 seconds? Homework Equations Force acting = change in momentum/time that...

Homework Statement A “superball” of mass m bounces back and forth with speed v between two parallel walls, as shown. The walls are initially separated by distance l. Gravity is neglected and the collisions are perfectly elastic. If one surface is slowly moved toward the other with speed V...

Homework Statement [/B]Homework Equations For this problem I have calculated the average force as ∫ Fdt/ ∫dt And using a(acceleration)=2h(height)/t2 and calculating the numerator it comes out -2m(mass)h/t ,but what will be the limit of the intergral in that case ?? Of course the...

Homework Statement A 0.170-kg baseball pitched horizontally at 36.0 m/s strikes a bat and is popped straight up to a height of 36.0 m. If the contact time between bat and ball is 2.0 ms, calculate the magnitude of the average force between the ball and bat during contact. ##m_b=0.17kg##...

Homework Statement Nikhil is probably eating his daily snack at this time. Old Man Miller comes back from the store and takes the 0.150kg sandwich from Nikhil as he begins to run away. Nikhil is running at 7.5m/s away from me when I hit him in the head with the sandwich that was moving at...

1.Problem statement Prove the average external force of a system of particles N starting from rest and ending at rest is zero.Homework Equations If the system moves periodically prove the av. external force is zero in a period The Attempt at a Solution I don't quite understand what i am asked...

Homework Statement What is the Average Force between m1 and m2. Show all work. Note that the masses are both at rest, and begin to push off of each other in opposite directions. Their velocity is measured when they reach 20cms distance. (I calculated the velocity when they reached this point...

Homework Statement A person jumps from the roof of a house 4.2-mhigh. When he strikes the ground below, he bends his knees so that his torso decelerates over an approximate distance of 0.66 m . If the mass of his torso (excluding legs) is 43 kg , find the magnitude of the average force exerted...

1. A baseball of mass 0.1 kg is moving horizontally at a speed of 40 m/s when it is stuck by a bat. It leaves the bat in a direction at an angle φ = 30◦ above its incident path and with a speed of 50 m/s. • Find the impulse the bat exerts on the ball. • Assuming the collision lasts for 0.0015...

Homework Statement A particle of mass 5.0kg travels initially with a velocity of 8.0m/sˆı and then interacts with a particle of mass 6.0kg which was initially at rest. After the interaction the 5.0kg mass travels at a speed of 4.0m along a direction which makes an angle of 53◦ with the x-axis...

Homework Statement A golf ball is struck by a golf club and sent flying down range at an angle of 30 degrees to the ground and lands 150m downrange. If the mass of the ball is 0.045 kg and the collision of the ball and club lasted 0.01s, what was the average force applied by the club...

Homework Statement Homework Equations ∑Fav = mv2 - mv1 The Attempt at a Solution We have to separate v in x dir and y dir?

1. How do you calculate the average force on a piston in one stroke from TDC to BDC given the following Kg forces and their distances in mm from TDC? 1 mm 2 mm 3 mm 4 mm 5 mm 6 mm 7 mm 8 mm 9 mm 10 mm 12 mm 13 mm 9.9 Kg 7.8 Kg 6.3 Kg 5.3 Kg 4.4 Kg 3.8 Kg 3.2...

Homework Statement When it crashes into a bridge support that does not move, a car goes from 85 km/h to 0 in 1.23 m. A) What is the impulse delivered to the 70-kg driver by the seat belt, assuming the belt makes the driver's motion identical to the car's motion? Assume that the initial...

Homework Statement When an 98.0-g piece of toast is inserted into a toaster, the toaster's ejection spring is compressed 7.20 cm. When the toaster ejects the toasted slice, the slice reaches a height of 3.4 cm above it's starting position. What is the average force that the ejection spring...

Homework Statement A 65 kg man jumps at a velocity of 1.8 m/s. The contact time is 0.45 seconds. Find the average force exerted by the man. Homework Equations F=ma+mg The Attempt at a Solution F=65*(1.8/.45)+65*9.81 I'm not sure if the equation has to be divided by the contact time, .45...

1. Question A 0.145kg baseball moving horizontally at 35.0m/s strikes a bat and is popped straight up to a height of 55.6m before turning around. If the contact time is 0.50ms, calculate the average force on the ball during the contact. Homework Equations p=mv Δp=mΔv=fΔt Ek=0.5mv^2 (?) Ep=mgh...

Homework Statement Just before hitting the ground, a partially inflated 0.625kg basketball has a speed of 3.30m/s. Then it loses half of its kinetic energy as it bounces. (A)What is the ball's speed immediately after it bounces?(B) If the ball is in contact with the ground for 9.25ms, what is...

Homework Statement Rocket engine expends 1150 kg of gas in 1 second, with a velocity of -4.50×10^4 m/s. Calculate the average force exerted on the rocket by the gas during that 1.0 second interval Homework Equations F= m(delat)v / (delta)t The Attempt at a Solution F= (1150kg)(-45000m/s) / 1...

Homework Statement A 500hp Mustang is able to push this 1750kg car down a 410m drag strip in a time of 11.5s. a) What is the work done by the car? b) What is the average force during the car's motion. Given: Power = 500hp = 372000w Mass = 1750kg Distance = 410m...

Homework Statement The acceleration-time graph above is drawn for a body which starts from rest and moves in a straight line. The body is of mass 10 kg. Use the graph to find: (a) the average distance traveled in 15 s, (b) the average force acting over the whole 15 s period. Answers: (a)...

Homework Statement A rifleman is shooting at a target at a firing range. The rifle has a mass of 4.0kg. When the gun's trigger is pulled, a bullet of mass of 10g will exit the rifle's barrel at a speed of 800m/s. The rifle is stationary at the instant the trigger is pulled. Given that the rifle...

Homework Statement I am stuck on the last problem. Homework Equations Just the error propagation equations The Attempt at a Solution I initially used the multiplication error propagation formula. So the average force would be the impulse divided by the time, the same thing as the impulse...

Homework Statement A ball hits the wall in a normal direction with v=10m/s. After the hit which lasted 0.2 Seconds, it turned in the same direction with v=10m/S. Knowing that its mass is 0.5 kg, find the average force that hit the wall. Homework Equations F=m*a, a= (v-v0)/t The Attempt at a...

Homework Statement The problem says: "A record rainstorm produced 304.8 mm (approximately 1 ft) of rain in 42 min. Estimate the average force that the rain exerted on the roof of a house that measures 10 m * 16 m. Indicate any assumptions you made. (Note: density of water is 1000 kg/m3"...

Homework Statement A 5kg box is tossed across the floor at 4 m/s and slides to a stop in 3 seconds. What is the average force of friction? Homework Equations I believe the answer is 6.66N, I found that because the problem was pulled from the book. But I am trying to understand how and why...

I'm doing a catapult project but I'm sort of confused. I need to find the spring constant in order to get the elastic potential energy. The force of pulling back the catapult lever to 36 degrees above the horizontal is 4.2 N. Right before the lever is at rest, 90 degrees, the force is 1.4 N. One...

Homework Statement Problem 3.12 from Kleppner & Kolenkow A ski tow consists of a long belt of rope around two pulleys, one at the bottom of a slope and the other at the top. The pulleys are driven by a husky electric motor so that the rope moves at a steady speed of 1.5 m/s. The pulleys are...

Homework Statement [/B] A 0.145- kg baseball with an initial speed of 20 m/s rebounds with a speed of 36 m/s after being struck with a bat. If the duration of contact between ball and bat was 2.4 ms, what was the magnitude of the average force between ball and bat? Homework Equations Δ...

Homework Statement Baseball(0.145kg) pitch is pitched horizontally at 32m/s, ball pops straight up to a height of 36.5m. If the contact time between bat and ball is 2.5ms, calculate the average force between the ball and the batt during contact. Homework Equations Favg = Δp/t KE=KE The...

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. [FONT=Arial]What I did on...

Homework Statement Suppose an oxygen molecule traveling at the speed of 484 m/s bounces back and forth between opposite sides of a cubical vessel 0.1 m on a side. What is the average force the molecule exerts on one of the walls of the container? Homework Equations F=p/t The Attempt at a...

Homework Statement A rocket with a mass of 7.2 x 10^4 kg starts from rest in outer space and fires its thrusters until it is moving with a velocity of 100 m/s. What was the average force on the rocket due to the thrusters? Homework Equations 1/2 mv^2 = Fxd The Attempt at a...

Homework Statement Consider a pair of electric dipoles ##\mu## and ##\mu'##, oriented in the directions ##(\theta,\phi)## and ##(\theta',\phi')## respectively; the distance ##R## between their centers is assumed to be fixed. The potential energy in this orientation is given by ##\varepsilon =...

Homework Statement A meteor with a mass of 1 kg moving at 20 km/s collides with Jupiter's atmosphere. The meteor penetrates 100 km into the atmosphere and disintegrates. What is the average force on the meteor once it enters Jupiter's atmosphere? (Note: ignore gravity). Homework...

Homework Statement A golf ball is struck by a golf club at 55 m/s at an angle of 28.0° above the horizontal. The mass of the ball is 45 grams and is in contact with the golf club for 15 ms. Calculate the average force exerted on the ball by the club.Homework Equations pi + FΔt = pf p = mΔv a...

Homework Statement A ball of mass m= .25kg is moving with an initial velocity of \vec{v}=(8.0\hat{x}+8.0\hat{y})(m/s). It rebounds from a wall and has a final velocity (after impact) of \vec{v}= (-5.0\hat{x}+6.0\hat{y})(m/s) a.) Determine the impulse exerted on the ball by the wall...

Show that the average force of gravity between Earth (mass = 6.0 X 10^24kg) and the moon (mass = 7.4X10^22 kg) is 2.1X10^20 N. The average earth-moon distance is 3.8 X 10^8 m

Homework Statement A football player whose mass is 85 kg throws a football with a mass of 0.8 kg against a post. The football hits the post traveling horizontally with a speed of 25 m/s, and then it bounces back with about the same speed. The football is in contact with the post for 0.05 s...

Physics average force need help! Homework Statement A coach is hitting pop flies to the outfielders. If the baseball (mass = 145 g) stays in contact with the bat for 0.09 s and leaves the bat with a speed of 84 m/s, what is the average force acting on the ball? Homework Equations...

This isn't actually a homework problem, I'm just wondering what I'm doing wrong: Homework Statement Say we've got a stationary brick wall, and a blob of jello with mass m is launched at the wall with speed v. The blob has length d along the direction of motion. The blob splatters...

Homework Statement A very hard rubber ball (m = 0.2 kg) is falling vertically at 3 m/s just before it bounces on the floor. The ball rebounds back at essentially the same speed. If the collision with the floor lasts 0.05 s, what is the average force exerted by the floor on the ball...