Test 3 Review Part 2

Students placed a steel ball at the top of a long piece of tubing track. As the ball rolled down the track, the students measured the distance the ball had traveled at various times. The graph below is a record of their data.

  

According to the information and graph, what unbalanced force is affecting the steel ball the most and how is it affecting the ball's motion?

• Friction with the track is the greatest unbalanced force, and it is causing the ball to slow down.

• Friction with the air is the greatest unbalanced force, and it is causing the ball to slow down.

• Gravity is the greatest unbalanced force, and it is causing the ball to speed up.

• The initial push of the ball is the greatest unbalanced force, and it is causing the ball to speed up.

Answer explanation

The upward curving line means the speed is increasing (accelerating). There is no mention of anyone pushing the ball.

Two Great Snipe birds are migrating. Both birds have a mass of 100 grams and are flying at 90 kilometers per hour. Bird R is flying 2.0 km above the ground, and Bird Q is flying 2.5 km above the ground.

Based on the information above, which statement best describes the energy of the two birds?

• Bird Q and Bird R have the same kinetic energy and potential energy.

• Bird Q and Bird R have the same kinetic energy but different potential energy.

• Bird Q and Bird R have no kinetic energy but have the same potential energy.

• Bird Q and Bird R have the same potential energy but different kinetic energy.

Answer explanation

Potential energy is based on height and mass. Kinetic energy is based on speed and mass. Same speed and mass = same kinetic energy. Their potential energy is the only thing that will be different because one is flying higher off the ground.

What is one of the major advantages of using hydroelectric power?

• It uses renewable natural resources.

• It is easily generated in most big cities.

• It can be generated from any area on Earth.

• It does not require special buildings or equipment

A bicycle rider is traveling up a hill. When the rider reaches the top of the hill, she stops to rest. Then she travels down the hill. The diagram shows the rider in the three different positions.

Which of these correctly describes the potential energy and the kinetic energy of the bicycle rider?

• As the rider reaches the bottom of the hill, her kinetic energy and her potential energy decrease.

• When the rider is at the top of the hill, her potential energy is the greatest, and her kinetic energy is the least.

• When the rider goes down the hill, her potential energy increases, and her kinetic energy decreases.

• As the rider reaches the bottom of the hill, her kinetic energy and her potential energy decrease.

Four balls made of different materials are placed on a tabletop 2 meters from the floor.

Which ball has the GREATEST amount of potential energy?

• Ball A

• Ball B

• Ball C

• Ball D

Answer explanation

Potential energy is increased by height and mass. The height is equal for all objects, so the object with the largest mass will have the most potential energy.

Students observed a turtle in the schoolyard. They measured the distance that the turtle traveled in 30 minutes. If the turtle walked 40 meters in that time, what was its average speed in meters per hour?

• 0.75 m/h

• 20 m/h

• 80 m/h

• 120 m/s

Answer explanation

Use the speed formula

Speed = Distance / Time

The answers are in hours, but the time is given in minutes. You must convert the time to the correct unit of measurement!

Which one is NOT an example of an inclined plane(s)?

• seesaw

• ramp

• screw

• axe

Which of these types of energy resources is MOST LIKELY to be used up by human activity?

• solar energy

• geothermal energy

• fossil fuel energy

• wind energy

What is a likely explanation of Kara's motion between the second and third hour of her ride?

• Kara is riding slowly to enjoy all the exhibits.

• Kara is giving her younger brother a ride

• Kara and her family are racing to see who is the fastest rider.

• Kara and her family stop to have lunch.

Which answer only lists renewable resources?

• biomass, solar, nuclear, wind

• oil, natural gas, wind, coal

• hydroelectric, solar, wind, geothermal

• geothermal, coal, hydroelectric, natural gas