1.  A 70 kg skydiver jumps out of the plane. What is

a)  the acceleration of the skydiver the moment she steps out of the plane?

b)  the acceleration of the skydiver before the parachute opens if the air resistance is 450 N.

c)  the acceleration of the skydiver after the parachute opens if the air resistance is 1700 N.

d)  the air resistance of the skydiver/parachute combination at terminal velocity.

2.  Forces of 100 N [N] and 80 N [W] act simultaneously on an object of mass 10 kg.

a)  What is the net force acting on the object?

b)  What is the acceleration of the object?

3.  A speedboat is pulling two water skiers, using two ropes attached to the back of the boat. Each rope makes an angle of 30° on either side of the boat’s axis. The force exerted by each rope is 400 N.

If the boat is moving in a straight line at a constant speed, what force must if be exerting to keep the pair of skiers moving?

4.  A gardener pushes down along the handle of a lawn mower of 20 kg with a force of 15 N. The handle makes an angle of 60° with the ground.

a)  Calculate the instantaneous acceleration of the mower if the frictional force between its wheels and the ground at that instant is 5 N.

b)  What is the normal force?

5.  A man drags a package across the floor with a force of 40 N. The mass of the package is 10 kg. If the acceleration of the package is 3.5 m/s2, and the friction can be neglected,

a)  at what angle to the horizontal does the man pull?

b)  what is the normal force?

Answers: 1 a) 9.8 m/s2 [down], b) 3.37 m/s2 [down], c) 14.5 m/s2 [up], d) 686 N [up] 2) a) 128 N [38.7º W of N], b)12.8 m/s2 [38.7° W of N], 3) 693 N, 4) a) 0.125 m/s2 [forward], b) 209 N [up], 5) a) 29.0°, b) 78.6N,