Collisions: Mastery Test Quiz

Select all the correct answers. Which situations describe an elastic collision?

• Two glass marbles bounce off each other.

• Rodrick flops onto his sofa and sinks into the cushion.

• A tossed water balloon flattens when it lands on the grass.

• A bowling ball knocks over five pins.

Answer explanation

An elastic collision is one where kinetic energy is conserved. The two glass marbles bouncing off each other and the bowling ball knocking over pins both demonstrate this, while the other scenarios involve inelastic behavior.

Select the correct answer. Erica throws a tennis ball against a wall, and it bounces back. Which force is responsible for sending the ball back to Erica?

• the force that the ball exerts on the wall

• the frictional force between the wall and the ball

• the acceleration of the ball as it approaches the wall

• the normal force that the wall exerts on the ball

Answer explanation

The normal force that the wall exerts on the ball is responsible for sending the ball back to Erica. This force acts perpendicular to the wall and causes the ball to bounce back after impact.

Select the correct answer. Which unit abbreviation is a measurement of force?

• m/s

• m/s²

• N

• N/s

Answer explanation

The correct unit abbreviation for a measurement of force is 'N', which stands for Newton. The other options represent different measurements: 'm/s' is speed, 'm/s²' is acceleration, and 'N/s' is not a standard unit.

A free-falling golf ball strikes the ground and exerts a force on it. Which sentences are true about this situation?

• A golf ball striking the ground is a collision.

• The ground exerts an equal force on the golf ball.

• The ground doesn’t exert a force on the golf ball.

• The force is zero because the golf ball has little mass.

Answer explanation

A golf ball striking the ground is indeed a collision, and according to Newton's third law, the ground exerts an equal force back on the golf ball. The other statements are incorrect.

Select the correct answer from each drop-down menu. Danica observes a collision between two vehicles. She sees a large truck driving down the road. It strikes a small car parked at the side of the road. Complete the passage summarizing the collision. On colliding, the truck applies a force on the stationary car, and the stationary car applies a smaller and opposite force on the truck. The front of the truck is designed to crumple in order to apply maximum force on the stationary car, which protects the well-being of the passengers.

(a)  

• lower the force of the impact

• apply maximum force on the stationary car

• an equal

• a smaller

• a greater

Answer explanation

The correct choice is 'apply maximum force on the stationary car' because the truck's design allows it to exert a strong force on the car, ensuring effective impact while protecting its passengers.

Select the correct answer from each drop-down menu. In an experiment, Mary compares a collision of two 1-kilogram steel balls with a collision of two 1-kilogram foam rubber balls. She makes sure that, except for the material, the two collisions are the same. Mary finds that the force of impact of the steel ball collision is greater than the force of impact of the foam rubber ball collision. From her force measurements, Mary concludes that the foam rubber balls’ acceleration during the collision was the same as the steel balls’ acceleration. She concludes that the collision between the foam rubber balls is an elastic collision.

(a)  

• elastic

• inelastic

• greater than

• less than

• the same as

Answer explanation

Mary's conclusion that the foam rubber balls' collision is elastic is incorrect. Since the steel balls had a greater force of impact, the foam rubber balls must have undergone an inelastic collision, where kinetic energy is not conserved.

Select the correct location on the image. Matthew drops a ball and watches it bounce back up from the ground. He draws a force diagram that shows the forces when the ball collides with the ground. Which diagram correctly shows the forces involved?