Physics: Momentum and Collisions Flashcards
What is the equation for momentum?
P=m x v
What does p stand for?
Momentum
What is momentum?
A quantity defined as the product of the mass and velocity of an object.
A deer with a mass of 146 kg is running head-on towards you with a speed of 17 m/s. You are going north. Find the momentum of the deer
2482 kg*m/s South
A 21 kg child on a 5.9 kg bike is riding with a velocity of 4.5 m/s to the Northwest. What is the momentum of the bike, the child, and both of them?(Remember sig figs)
Child: 95 kgm/s northwest
Bike: 27 kgm/s northwest
Both: 120 kg*m/s northwest
What velocity must a 1210 kg car have in order to have the same velocity of a pickup truck that has a mass of 2250 and a velocity of 25 m/s east?
46 m/s east
What is the impulse-momentum theorem?
F x delta t = delta p or force times change in time equals change in momentum
What is the impulse in the impulse momentum theorem?
F x delta t
How was Newton’s second law originally expressed?
Force = change in momentum/change in time
A 0.50 kg football is thrown with a velocity of 15 m/s to the right. A stationary receiver catches the ball and brings it to rest in 0.020 s. What is the force exerted on the ball by the receiver?
380 N to the left
An 82 kg man drops from rest on a diving board 3.0 m above the surface of the water and comes to rest 0.55 s after reaching the water. What is the net force on the diver as he is brought to rest? (Assume g = 9.81 m/s^2)
0.78 N up
A 0.40 kg soccer ball approaches a player horizontally with a velocity of 18 m/s north. The player strikes the ball and causes it to move in the opposite direction at a velocity of 22 m/s. What impulse was delivered to the ball by the player?
16 kg*m/s south
A 0.50 kg object is at rest. A 3.00 N force to the right acts on the object during a time interval of 1.50 s.
a. What is the velocity of the object at the end of this interval?
b. At the end of this interval, a constant force of 4.00 N to the left is applied for 3.00 s. What is the velocity at the end of the 3.00 s?
a. 9 m/s
b. -15 m/s
The speed of a particle is doubled.
a. By what factor is its momentum changed? b. What happens to its kinetic energy?
a. It is doubled
b. quadrupled
A pitcher claims he can throw a 0.145 baseball with as much momentum as a speeding bullet. Assume that a 3.00 g bullet moves at a speed of 1.5x10^3 m/s
a. What must the baseball's speed be if the pitcher's claim is valid? b. Which has the greater kinetic energy, the ball or the bullet?
a. 31.034 m/s
b. The ball
A 0.42 soccer ball is moving downfield with a velocity of 12 m/s. A player kicks the ball so that it has a final velocity of 18 m/s downfield.
a. What is the change in the ball's momentum? b. Find the constant force exerted by the player's foot if the two are in contact for 0.020 s.
a. 2.52 kg*m/s downfield
b. 126 N
What is the unit for momentum?
kg*m/s
When a force is exerted on an object, does a large force always produce a larger change in the objects momentum than a smaller force? Explain.
No, because if the smaller force is applied over a longer amount of time, it can have a larger effect, due to the impulse momentum theory.
What is the law of conservation of momentum?
m1v1,i +m2v2,i = m1v1,f + m2v2,f
Total initial momentum = total final momentum
A 63.0 kg astronaut is on a space walk when his tether line to the shuttle breaks. The astronaut is able to throw a spare 10.0 kg oxygen tank in a direction away from the shuttle with a speed of 12.0 m/s, propelling the astronaut back to the shuttle. Assuming that the astronaut starts from rest respective to the shuttle, find the astronaut’s final speed with respect to the shuttle after the tank is thrown.
1.9 m/s
An 85 kg fisherman jumps from a dock into a 135 kg rowboat at rest an the west side of the dock. If the velocity of the fisherman is 4.30 m/s to the west as he leaves the dock, what is the final velocity of the fisherman and the boat?
1.66 m/s to the west
What is a perfectly inelastic collision?
a collision in which two objects stick together after colliding
Is kinetic energy conserved in perfectly inelastic collisions?
No
What is the equation for perfectly inelastic collisions?
m1v1,i+m2v2,i=(m1+m2)vf
A 1500 kg car travelling at 15.0 m/s to the south collides with a 4500 kg truck initially at rest at a stoplight. the car and truck stick together and move together after the collision. What is the final velocity of the two-vehicle mass?
3.8 m/s south
What is an elastic collision?
A collision in which the total momentum and total kinetic energy are conserved.
Is kinetic energy conserved in elastic collisions?
Yes
