momentum and impulse

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 If the ball bounces, then there is an additional velocity change sending the ball back upwards opposite the original direction. Thus, for the same collision time, bouncing involves a greater velocity change, a greater momentum change, and therefore a greater impulse.

In the graph above, impulse can be found

by calculating the area under the curve

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 ________________.

doubled Momentum is directly related to the mass of the object. So for the same speed, a doubling of mass leads to a doubling of momentum.

When something undergoes an impulse, it was affected by the quantities of ______________ and _________

force, time

If an object at rest undergoes an impulse, what will happen to the object?

it will speed up (positive impulse)

A relatively large force acting for a relatively long amount of time on a relatively small mass will produce a relatively ______. List all that apply.

large velocity change

Momentum

mass kg x velocity m/s an object has momentum if it is moving mass in MOTION

21. Two objects, A and B, have the same size and shape. Object A is twice as massive as B. The objects are simultaneously dropped from a high window on a tall building. (Neglect the effect air resistance.) The objects will reach the ground at the same time but object A will have a greater ___. Choose all that apply.

momentum

An object which is moving at a constant speed has

momentum

The Impulse-Momentum Theorem states that ________________________________.

momentum is changed by an impulse

if areas are equal (impulse on graph)

returns to same speed (positive then negative)

The impulse-momentum theorem?

states that the impulse on an object equals the object's final momentum minus the object's initial momentum FΔt = Δp or FΔt = mΔv

Impulse

the change of momentum of an object when the object is acted upon by a force for an interval of time N x S

If mass and collision time are equal, then impulses are greater on objects which rebound (or bounce).

FALSE

The momentum of any object that is at rest is

0 Objects at rest do not have momentum

Two carts move along a track towards each other. Cart A has a mass of .450 kg and moves toward the right with a speed of 0.850 m/s. Cart B has a mass of .300 kg and moves toward the left with a speed of 1.12 m/s. What is the total momentum of the two-cart system?

0.047 kg ∙ m/s toward the right

Two ice skaters suddenly push off against one another starting from a rest position. The 45-kg skater acquires a speed of 0.375 m/s relative to the ice. What speed does the 60-kg skater acquire relative to the ice?

0.28 m/s

The astronauts shown above are of equal mass, 75-kg. What is their velocity after they collide and stick

1-m/s, left

A block of mass m = 4 kg and speed V is behind a block of mass M = 8 kg and speed of 0.5m/s as shown in the figure. The blocks collide and couple. After the collision, the blocks have a common speed of 0.90m/s. What is the magnitude of the initial velocity of the 4-kg block?

1.7 m/s

A 328-kg car moving at 19.1 m/s in the +x direction hits from behind a second car moving at 13.0 m/s in the same direction. If the second car has a mass of 790-kg and a speed of 15.1 m/s right after the collision, what is the velocity of the first car after this sudden collision?

14.0 m/s

A locomotive, M=5000kg, backs up at 5-m/s and "couples" to a stationary train car, m=1,000kg. After they couple at what velocity do they continue to move together?

4.17-m/s

which of the following is true of changes in momentum?

A large force may produce s small change in momentum by acting over a short period of time

Which of the following objects have momentum? Include all that apply.

An electron is orbiting the nucleus of an atom. A Yugo (a compact car) is moving with a constant speed. A small flea walking with constant speed across Fido's back. It matters not whether the object is of large mass or small mass, moving with constant speed or accelerating; if the object is MOVING, then it has momentum!

Which of the following statements are true about impulse?

Impulse is a vector quantity. Objects involved in collisions encounter impulses. The kg•m/s is equivalent to the units on impulse. An object which experiences a net impulse will definitely experience a momentum change. In a collision, the net impulse experienced by an object is equal to its momentum change. 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.

changes in momentum

Large mass over a long time Small mass over a short time

Which of the following statements are true about momentum?

Momentum is a vector quantity. An object which is moving at a constant speed has momentum. The momentum of an object varies directly with the speed of the object. Two objects of different mass are moving at the same speed; the more massive object will have the greatest momentum. An object with a changing speed will have a changing momentum. The direction of an object's momentum vector is in the direction that the object is moving.

Impulse is equal to change in momentum

Nᐧs is equal to kg ᐧ m/s

Consider the head-on collision between a lady bug and the windshield of a high speed bus. Which of the following statements are true? List all that apply.

The magnitude of the velocity change encountered by the bug is greater than that of the bus. The magnitude of the acceleration encountered by the bug is greater than that of the bus. In any collision between two objects, the force, impulse, and momentum change are the same for each object. However, the smaller mass object encounters a greater acceleration and velocity change.

When an object slows down, it has been affected by an IMPULSE.

True (negative impulse)

Which of the following statements are true about collisions?

Two colliding objects will exert equal forces upon each other even if their mass is significantly different. During a collision, an object always encounters an impulse and a change in momentum. In a collision, the two colliding objects could have different acceleration values.

A very massive object at rest has ________________ inertia.

a large

In any collision

the momentum change for each object is the same. Each object experiences the same force (Newton's third law) for the same amount of time, leading to the same impulse, and subsequently the same momentum change. Only the acceleration and the velocity change can differ for the two objects. The object with the least mass always receives the greatest velocity change and acceleration.

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 ___.

time of impact on both the block and the expert's hand is the same force on both the block and the expert's hand have the same magnitude impulse on both the block and the expert's hand have the same magnitude he lower mass object always receives the greater velocity change and acceleration.

A physics cart rolls along a low-friction track with considerable momentum. If it rolls at the same speed but has twice as much mass, its momentum is ____.

twice as large

The two quantities that make up momentum are __________ and ____________.

velocity, mass

A very massive object at rest has ________________ momentum.

zero