BYU Physics 121 Chapter 9 Conceptual
Questions and answers correctly solved
2025
A driver who is protected by an airbag during a head-on collision is less likely
to be seriously injured than an unprotected driver. This is because the airbag -
correct answer ✔increases the time interval over which the impulse is
experienced. The total impulse is always the same, because the change in
momentum is the same, but the impulse is also equal to the average force
times the time over which it is exerted. If you extend the time, then you
decrease the average force, which decreases the probability of injury.
A bullet moving horizontally strikes and sticks in a block of wood that is free to
move on a horizontal, level, frictionless surface. The block has a much greater
mass than the bullet. What becomes of most of the momentum of the bullet? -
correct answer ✔It becomes the total momentum of the block plus the bullet.
Block A is traveling due north with a velocity of 10 m/s. Block B is traveling
due east with a velocity of 1 m/s. Block A has 10 times the mass of block B.
The two blocks stick together after the collision. After the collision the two
blocks - correct answer ✔travel slightly east of north.
A body is made up of multiple parts that are attached to each other by several
compressed springs. It has been shot from a cannon and at the peak of its
trajectory the springs are released, causing the parts to fly apart. The center
of mass of the two parts - correct answer ✔continues along the same
parabolic path as before.
A rocket fully loaded with fuel is sitting in space far from any other body. The
engine is started and the rocket starts to spew exhaust gases out of the back
of the engine. Which of the following explains what happens? - correct
Questions and answers correctly solved
2025
A driver who is protected by an airbag during a head-on collision is less likely
to be seriously injured than an unprotected driver. This is because the airbag -
correct answer ✔increases the time interval over which the impulse is
experienced. The total impulse is always the same, because the change in
momentum is the same, but the impulse is also equal to the average force
times the time over which it is exerted. If you extend the time, then you
decrease the average force, which decreases the probability of injury.
A bullet moving horizontally strikes and sticks in a block of wood that is free to
move on a horizontal, level, frictionless surface. The block has a much greater
mass than the bullet. What becomes of most of the momentum of the bullet? -
correct answer ✔It becomes the total momentum of the block plus the bullet.
Block A is traveling due north with a velocity of 10 m/s. Block B is traveling
due east with a velocity of 1 m/s. Block A has 10 times the mass of block B.
The two blocks stick together after the collision. After the collision the two
blocks - correct answer ✔travel slightly east of north.
A body is made up of multiple parts that are attached to each other by several
compressed springs. It has been shot from a cannon and at the peak of its
trajectory the springs are released, causing the parts to fly apart. The center
of mass of the two parts - correct answer ✔continues along the same
parabolic path as before.
A rocket fully loaded with fuel is sitting in space far from any other body. The
engine is started and the rocket starts to spew exhaust gases out of the back
of the engine. Which of the following explains what happens? - correct
