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

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?

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?

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?

Explain how force, mass, and acceleration are related by Newton's second law of motion.

A 240-kg snowmobile travels at $16 \mathrm{~m} / \mathrm{s}$. The mass of the driver is $75 \mathrm{~kg}$. What is the momentum of the snowmobile and driver?

In what ways were Irish and German immigrants to the United States similar and different?

Who were the nativists?

Which of the following would be the best Web site to find information about life in the South before the Civil War? a. a Civil War historian's homepage b. a collection of autobiographies written by slaves c. a site with information about how to grow cotton d. a collection of biographies of inventors

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

a. What is momentum? b. What is the momentum of a parked car? c. Why is it important for drivers to allow more distance between their cars when they travel at faster speeds?

a. What is the law of universal gravitation? b. How do mass and distance affect the gravitational attraction between objects? c. How would your weight change on the surface of an Earth-sized planet whose mass was greater than Earth's? Why?