Multiple choice.

The airbag in a car works in a collision by . . .
a. increasing the time of the impact to the person.
b. reducing the impulse to the person.
c. reducing the momentum of the person.
d. increasing the force on the person.

A cannonball shot from a cannon with a long barrel will have a greater muzzle velocity because the cannonball receives a greater . . .
a. force.
b. impulse.
c. both force and impulse.
d. neither force nor impulse.
.

How much kinetic energy does a 1 kg ball have if it has a velocity of 10 m/s?

a. 100 J.
b. 50 J.
c. 10 J.
d. 5 J.

To find the answer to the first question, we need to understand how an airbag works in a car collision. The purpose of an airbag is to provide protection to the occupants of the vehicle during a collision. When there is a collision, the airbag rapidly inflates to create a cushioning effect.

Let's analyze each option to determine the correct answer:

a. Increasing the time of the impact to the person: This option is not correct because increasing the time of impact would actually increase the force exerted on the person, which can be dangerous.

b. Reducing the impulse to the person: Impulse is the change in momentum experienced by an object. In this case, the airbag reduces the impulse by increasing the time it takes for the collision to occur, thus spreading out the force and reducing the overall impact.

c. Reducing the momentum of the person: This option is not correct because the airbag doesn't directly affect the momentum of the person. Rather, it reduces the force applied to the person during a collision.

d. Increasing the force on the person: This option is not correct because the airbag is designed to reduce the force applied to the person, not increase it.

Therefore, the correct answer to the first question is (b) reducing the impulse to the person.

Moving on to the second question, the greater muzzle velocity of a cannonball shot from a cannon with a long barrel is determined by:

a. Force: The force applied to the cannonball determines its acceleration, but it doesn't necessarily determine its muzzle velocity. So, this option is not correct.

b. Impulse: Impulse is the change in momentum experienced by the cannonball when it is shot out of the cannon. A longer barrel provides a longer distance over which the force is applied, resulting in a greater impulse and ultimately a greater muzzle velocity.

c. Both force and impulse: This option is not correct because while both force and impulse have a role in determining the muzzle velocity, the length of the barrel primarily affects the amount of impulse, not the force.

d. Neither force nor impulse: This option is not correct because both force and impulse are involved in the calculation of muzzle velocity, with impulse being the more significant factor.

Therefore, the correct answer to the second question is (b) impulse.