Physics Momentum:
Suppose that you're driving down the highway and a moth crashes into the windshield of your car. Which undergoes the greater acceleration? a. the moth b. your car c. both the same
A
Formula for Momentum
P=m v
Conservation of momentum formula
Psystem = Psystem
Impulse
is the change of momentum of an object when the object is acted upon by a force for an interval of time.
Kinetic Energy Formula
1/2 m v^2
A 6.0-kg object moving at 3.0 m/s encounters a 40-Newton resistive force over a duration of 0.20 seconds. The final momentum of this object is approximately _________ kg • m/s.
10
A 3.0-kg object moving at 6.0 m/s encounters a 20-Newton resistive force over a duration of 0.10 seconds. The momentum change (magnitude only) experienced by this object is approximately _________ N • s.
2.0
Two carts are at rest upon a track and connected by a compressed spring. The spring is released, pushing upon the two carts such that it propels them in opposite directions. One cart has a mass of '2M' and is propelled with a speed of 30 cm/s. The second cart has a mass of 'M' and is propelled with a speed of ____ cm/s.
60 cm/s
Elastic Collision
A collision where both momentum and kinetic energy are conserved.
Which of the following statements is true about momentum? a. Momentum is a vector quantity. b. The standard unit on momentum is the Joule. c. An object with mass will have momentum. d. An object which is moving at a constant speed has momentum. e. An object can be traveling eastward and slowing down; its momentum is westward. f. Momentum is a conserved quantity; the momentum of an object is never changed. g. The momentum of an object varies directly with the speed of the object. h. Two objects of different mass are moving at the same speed; the more massive object will have the greatest momentum. i. A less massive object can never have more momentum than a more massive object. j. Two identical objects are moving in opposite directions at the same speed. The forward moving object will have the greatest momentum. k. An object with a changing speed will have a changing momentum.
A, D, G, H, K
Which of the following statements are true about collisions? A. Two colliding objects will exert equal forces upon each other even if their mass is significantly different. B. During a collision, an object always encounters an impulse and a change in momentum. C. During a collision, the impulse which an object experiences is equal to its velocity change. D. The velocity change of two respective objects involved in a collision will always be equal. E. While individual objects may change their velocity during a collision, the overall or total velocity of the colliding objects is conserved. F. In a collision, the two colliding objects could have different acceleration values. G. In a collision between two objects of identical mass, the acceleration values could be different. H. Total momentum is always conserved between any two objects involved in a collision. I. When a moving object collides with a stationary object of identical mass, the stationary object encounters the greater collision force. J. When a moving object collides with a stationary object of identical mass, the stationary object encounters the greater momentum change. K. A moving object collides with a stationary object; the stationary object has significantly less mass. The stationary object encounters the greater collision force. L. A moving object collides with a stationary object; the stationary object has significantly less mass. The stationary object encounters the greater momentum change.
A,B,F
Cars are equipped with padded dashboards. In collisions, the padded dashboards would be safer than non-padded ones because they ____. List all that apply. a. increase the impact time b. decrease an occupant's impulse c. decrease the impact force d. none of the above
A,C
Which of the following objects have momentum? Include all that apply. a. An electron is orbiting the nucleus of an atom. b. A UPS truck is stopped in front of the school building. c. A Yugo (a compact car) is moving with a constant speed. d. A small flea walking with constant speed across Fido's back. e. The high school building rests in the middle of town.
A,C,D
Inelastic Collision
An collision is one in which part of the kinetic energy is changed to some other form of energy in the collision.
When a mass M experiences a velocity change of v in a time of t, it experiences a force of F. Assuming the same velocity change of v, the force experienced by a mass of 2M in a time of (1/2)t is ____. a. 2F b. 4F c. (1/2)*F d. (1/4)*F e. none of these
B
Which of the following statements are true about impulse? A. Impulse is a force. B. Impulse is a vector quantity. C. An object which is traveling east would experience a westward directed impulse in a collision. D. Objects involved in collisions encounter impulses. E. The Newton is the unit for impulse. F. The kg•m/s is equivalent to the units on impulse. G. An object which experiences a net impulse will definitely experience a momentum change. H. In a collision, the net impulse experienced by an object is equal to its momentum change. J. A force of 100 N acting for 0.1 seconds would provide an equivalent impulse as a force of 5 N acting for 2.0 seconds.
B,D,F,G,H,I
Suppose that you're driving down the highway and a moth crashes into the windshield of your car. Which undergoes the greater change is momentum? a. the moth b. your car c. both the same
C
Suppose that you're driving down the highway and a moth crashes into the windshield of your car. Which undergoes the greater force? a. the moth b. your car c. both the same
C
The Impulse
Change in Momentum is equal to
Consider a karate expert. During a talent show, she executes a swift blow to a cement block and breaks it with her bare hand. During the collision between her hand and the block, the ___. a. time of impact on both the block and the expert's b. hand is the same b. force on both the block and the expert's hand have the same magnitude c. impulse on both the block and the expert's hand have the same magnitude d. all of the above.
D
Suppose that Paul D. Trigger fires a bullet from a gun. The speed of the bullet leaving the muzzle will be the same as the speed of the recoiling gun ____. a. because momentum is conserved b. because velocity is conserved c. because both velocity and momentum are conserved d. only if the mass of the bullet equals the mass of the gun e. none of these
D
Change in Momentum
Equal to the Impulse, m(vf-vi)
True or False: A ball is dropped from the same height upon various flat surfaces. For the same collision time, impulses are smaller when the most bouncing take place.
False
Momentum
Mass in Motion
Units of Impulse
N s
"Perfect/Completely" Inelastic collision
The colliding objects stick together after the collision. The momentum is conserved. Kinetic energy is not conserved.
The momentum is doubled
When the Mass of a moving object is doubled.
Increased
When the time for a momentum change is shortened the Force is
increased by a factor 9X
When the velocity of an object is tripled, its Kinetic Energy is
Which of these collisions demonstrates momentum conservation?
ac
If I increase the duration of time for an impulse, the FORCE will
decrease, (big t, little f)
A truck driving along a highway road has a large quantity of momentum. If it moves at the same speed but has twice as much mass, its momentum is ________________. a. zero b. quadrupled c. doubled d. unchanged
doubled
An impulse occurs when _________ is acting upon an object for a given amount of _________ in order to cause a change in _________
force, time, and momentum
An object that has momentum can be best be described as
having its mass in motion
Momentum Units
kg m/s
A rightward moving object is slowing down. The direction of its momentum is
rightward
During the collision, the golf club encounters _______ force, __________ impulse, ___________ momentum change, and __________ acceleration
the same, the same, the same, a smaller
Compared to Object B, Object A has ________ the momentum
two times