Gravity and Friction Review

After throwing a basketball through the net, Anna observed the ball as it hit the ground. Which is most likely responsible for the ball hitting the ground?

• friction

• gravity

• mass

• speed

Chris climbs onto a skateboard ramp halfway between the top and the bottom of the ramp. Because gravity acts on Chris, which is most likely to happen?

• He won't move.

• He will roll up the ramp.

• He will roll down the ramp.

• He will float above the ramp.

Which investigation will BEST test the effects of gravity on moving objects?

• pencils falling from the same height

• balloons floating upward from the same height

• a bicycle speeding up on a flat surface

• a ball slowing down on a flat surface

Katie was pulling a sled with her puppy in it. Katie’s sister then got into the sled with the puppy. How would the sled’s speed most likely change after Katie’s sister got into the sled?

• The speed would increase due to the change in mass.

• The speed would decrease due to the change in mass.

• The speed would increase due to the change in friction.

• The speed would decrease due to the change in gravity.

Ana is pushing a wheelbarrow of rocks. She stops and unloads half of the rocks. How will this effect the force needed to move the wheelbarrow?

• Gravity is increased, making the wheelbarrow easier to move.

• Gravity is decreased, making the wheelbarrow harder to move.

• Friction is increased, making the wheelbarrow harder to move.

• Mass is decreased, making the wheelbarrow easier to move.

What has the greatest impact on a free-falling object?

• friction

• gravity

• inertia

• momentum

Billy rolls a toy truck filled with marbles across the kitchen floor. He then dumps the marbles before rolling it back to his starting location. How would the speed of the truck most likely change on the way back?

• The speed would increase due to friction.

• The speed would increase due to a change in mass.

• The speed would decrease due to a change in mass.

• The speed would decrease due to a change in gravity.

Chris attaches a sheet of sandpaper to the top of his skateboard. How does this sandpaper most likely affect Chris’s skateboarding?

• It protects the skateboard from any damage.

• It allows Chris to steer the skateboard in a variety of directions.

• It reduces the effect gravity has on the skateboard as he moves down the ramp.

• It increases friction between the skateboard and Chris’s foot to keep him from slipping.

Four cubes made of different materials are moving down a plastic slide. Which cube would experience the greatest amount of friction?

• the cube made of ice

• the cube made of sandpaper

• the cube made of smooth plastic

• the cube made of polished stone

The gravitational force of the Sun is strong enough to hold all the planets of the solar system in orbit many millions of miles away. Which BEST describes why objects having far less mass on the surface of these planets are not pulled off and into the Sun?

• The objects have too little mass to be affected by the Sun.

• The objects have more mass on the planets than on the Sun.

• The objects are held by the greater combined gravity of all the planets.

• The objects are more strongly affected by the gravity of the planet on which they are found.