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

Aplayground slide is 8.80 ft long and makes an angle of 25.0° with the horizontal. a 63.0-kg child, initially at the top, slides all the way down to the bottom of the slide. (a) choosing the bottom of the slide as the reference configuration, what is the system's potential energy when the child is at the top and at the bottom of the slide? what is the change in potential energy as the child slides from the top to the bottom of the slide? (include the sign of the value in your answer.)