A granite block is being slid at a constant speed across a horizontal concrete floor by an applied force parallel to the floor. Which pair of quantities could be used to determine the coefficient of friction for the granite on the concrete? A.) frictional force and speed of the block

B.) mass and normal force on the block

C.) frictional force and normal force on the block

D.) mass and speed of the block

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