When a bullet is fired from a gun, what is true about the momentum?
the gun has more momentum than the bullet, so the momentum is not conserved.
the bullet and gun have equal momenta in opposite directions, so the system's momentum is conserved.
the bullet has more momentum than the gun, so the momentum is not conserved.
the bullet and the gun have equal momenta in the same direction, so the system's momentum is conserved.

As part of your daily workout, you lie on your back and push with your feet against a platform attached to two stiff springs arranged side by side so that they are parallel to each other. when you push the platform, you compress the springs. you do an amount of work of 79.0 j when you compress the springs a distance of 0.230 m from their uncompressed length. (a) what magnitude of force must you apply to hold the platform in this position? (b)how much additional work must you do to move the platform a distance 0.230 m farther? (c) what maximum force must you apply to move the platform a distance 0.230 m farther?