. A sofa is pushed with a force of 450 N in the direction of the displacement of the sofa. If it is pushed 12 m, how much work is done on the sofa?

What is the coefficient of kinetic friction μk between the block and the tabletop?

What is the increase in density of a medium due to wave travel?

Astone is dropped from the upper observation deck of a tower, 250 m above the ground. (assume g = 9.8 m/s2.) (a) find the distance (in meters) of the stone above ground level at time t. h(t) = (b) how long does it take the stone to reach the ground? (round your answer to two decimal places.) s (c) with what velocity does it strike the ground? (round your answer to one decimal place.) m/s (d) if the stone is thrown downward with a speed of 2 m/s, how long does it take to reach the ground? (round your answer to two decimal places.) s