A 30 ky child running at 7 m/s jumps onto a 10 kg sled which was initially at rest. What will be the
velocity of the child+sled immediately after the child jumps on the sled?

Lets say that an object of a certain volume has a certin mass. what happens to its mass when you double its volume?

The sun generates both mechanical and electromagnetic waves. which statement about those wave is true?

Ahot-air balloonist, rising vertically with a constant speed of 5.00 m/s releases a sandbag at the instant the balloon is 40.0 m above the ground. after it is released, the sandbag encounters no appreciable air drag. compute the velocity of the sandbag at 0.250 s after its release.