In the balloon diagram above, why don't the two forces cancel each other out? A They are not equal. B They both act on the air. C They both act on the balloon. D They act on different objects.

What force makes it less likely for a person to slip on a dry sidewalk than on an icy sidewalk?

A gravity

B friction

C normal force

D magnetic force

Find the total momentum before and after collision. Is the law of conservation of momentum satisfied in this collision? Explain.

A dog pulls on a pillow with a force of 5 N at an angle of $37^{\circ}$ above the horizontal. Find the x and y components of this force.

Use the formula for momentum to find the momentum of each ball before and after the collision. Assume the mass of each ball is $0.4 \mathrm{~kg}$.

A 240-kg snowmobile travels at 16 m/s. The mass of the driver is 75 kg. What is the momentum of the snowmobile and driver?

A 7.3-kg bowling ball accelerates at a rate of 3.7 $m/s^2$. What force acts on the bowling ball?

When you drop a golf ball to the pavement, it bounces up. Is a force needed to make it bounce up? If so, what exerts the force?

Look at the diagram below of two students pulling a bag of volleyball equipment. The friction force between the bag and the floor is $15 \mathrm{~N}$. What is the net force acting on the bag? What is the acceleration of the bag?

Two lifeguards pull on ropes attached to a raft. If they pull in the same direction, the raft experiences a net force of 334 N to the right. If they pull in opposite directions, the raft experiences a net force of 106 N to the left. Draw a free-body diagram representing the raft for each situation.

You are moving fast on a skateboard when your wheel gets stuck in a crack on the sidewalk. Using the term inertia, explain what happens.

What kind of friction allows you to walk without slipping?

Two lifeguards pull on ropes attached to a raft. If they pull in the same direction, the raft experiences a net force of 334 N to the right. If they pull in opposite directions, the raft experiences a net force of 106 N to the left. Find the force exerted by each lifeguard on the raft for each situation. (Disregard any other forces acting on the raft.)

Suppose you are an astronaut making a space walk outside your space station when your jet pack runs out of fuel. How can you use your empty jet pack to get you back to the station?