A 35-kg crate rests on a horizontal floor, and a 65-kg person is standing on the crate. Determine the magnitude of the normal force that (a) the floor exerts on the crate and (b) the crate exerts on the person.

Traveling at a speed of $16.1 \textrm{ m/s}$, the driver of an automobile suddenly locks the wheels by slamming on the brakes. The coefficient of kinetic friction between the tires and the road is $0.720$. What is the speed of the automobile after $1.30 \textrm{ s}$ have elapsed? Ignore the effects of air resistance.

A space traveler weighs 540 N on earth. What will the traveler weigh on another planet whose radius is three times that of earth and whose mass is twice that of earth?

A rocket blasts off from rest and attains a speed of 45 m/s in 15 s. An astronaut has a mass of 57 kg. What is the astronaut's apparent weight during takeoff ?

The earth exerts a gravitational force on a falling raindrop, pulling it down. Does the raindrop exert a gravitational force on the earth, pulling it up? If so, is this force greater than, less than, or equal to the force that the earth exerts on the raindrop? Provide a reason for your answer. A raindrop has a mass of

$$5.2 \times 10 ^ { - 7 } \mathrm { kg }$$

and is falling near the surface of the earth. Calculate the magnitude of the gravitational force exerted (a) on the raindrop by the earth and (b) on the earth by the raindrop .

At an instant when a soccer ball is in contact with the foot of a player kicking it, the horizontal or x component of the ball's acceleration is $810 \mathrm{m} / \mathrm{s}^{2}$ and the vertical or y component of its acceleration is $1100 \mathrm{m} / \mathrm{s}^{2}$. The ball 's mass is 0.43 kg. What is the magnitude of the net force acting on the soccer ball at this instant?