3A Test: Laws of Motion HNRS

A 60-kilogram swimmer is doing laps in a pool. They push off from the wall using 150 newtons of force. What is the rate of the swimmer as they accelerate away from the wall?

• • 0.4 m/s²

• • 2.5 m/s²

• • 90 m/s²

• • 9,000 m/s²

Tags

NGSS.MS-PS2-2

Two items with different masses are shown falling from the same height.

Why does the acceleration not change between these two objects, despite having very different masses? Demonstrate this concept using Newton’s second law to calculate the force of gravity.

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NGSS.MS-PS2-2

NGSS.MS-PS2-4

A child pushed a toy car twice, as shown in the image.

Why did the acceleration change despite the mass being the same?

• • The child must have changed the starting position of the car the second time.

• • The speed of the car must have increased when it was pushed the second time.

• • The time that elapsed from start to finish decreased on the second push.

• • The child increased the force from the first to the second push.

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NGSS.MS-PS2-1

NGSS.MS-PS2-2

A cup of water with a mass of 250 grams is slid across a table with a force of 2 newtons. The cup tips over and spills. What forces were acting on the cup? What must the acceleration of the cup be in order to stop the cup? Include Newton’s three laws of motion in your explanations.

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NGSS.MS-PS2-2

A 70-kilogram person inside a car is accelerating at a rate of 0.5 m/s². What is the strength of the force required by the seat belt to stop the person completely?

• • 35 newtons, because the force of the seat belt is equal and opposite to the force of the person.

• • 150 newtons, because the force of the seat belt is equal and opposite to the force of the person.

• • It cannot be calculated, because the mass of the car is necessary to determine the force needed.

• • It cannot be calculated, because the mass of the seat belt is necessary to determine the force needed.

Tags

NGSS.HS-PS2-1

A car is traveling forward with people inside it. The driver slams on the brake, and the car comes to a quick stop. The people continue to travel forward, but the seat belts pull back on them and stop them. Which of Newton’s laws of motion is this an example of? Select TWO.

• • the first law, because the friction of the road prevents the car from sliding forever

• • the first law, because the people would continue moving forward without the force of the seat belt against them

• • the second law, because the acceleration of the car is equal to the force of the gas pedal times the mass of the people

• • the third law, because the force of the seat belt is equal and opposite to the force of the car

• • the third law, because the forces between the seat belts and people are equal and opposite

A billiard cue ball is hit with a lot of force, smacking into a rack of stationary balls at the beginning of the game. Many of the balls spread out on the table. Which of Newton’s laws does this example showcase, and why?

• • first law: the motion of the cue ball and stationary position of the racked balls before impact

    second law: the racked balls spreading out after impact

• • first law: the cue stick striking the cue ball

    third law: the stationary position of the racked balls

• • first law: the cue stick striking the cue ball

    second law: the collision of the cue ball with the stationary balls

    third law: the cue ball and stationary balls reacting to each other

• • first law: the motion of the cue ball and stationary position of the racked balls before impact

    second law: the racked balls spreading out after impact

    third law: the cue ball and stationary balls reacting to each other

Tags

NGSS.MS-PS2-1

Acceleration is dependent on both mass and force. Which answer correctly describes the acceleration of a skateboard?

• • The force needed to accelerate a 5 kg skateboard at 10 m/s2m/s2 is 20 N.  

• • If a skateboard accelerates at 10 m/s2m/s2 under a force of 20 N, its mass must be 2 kg.

• • If a 4 kg skateboard accelerates at 20 m/s2m/s2 as it falls, the force of gravity on the object must be 5 N.

• • The force needed to accelerate a 3 kg skateboard at 45 m/s2m/s2 is 15 N.

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NGSS.MS-PS2-2

This question has two parts. First, answer Part A. Then answer Part B.

Part A

A roller-coaster car is pulled up a big hill. At the top of the hill, it is released, and the car is pulled to the ground by gravity. Which of the following statements is true about the ride and Newton’s laws?

• • The car would continue on forever if there were no brakes at the end of the ride.

• • The car would slow to a stop due to friction if there were no brakes on the ride.

• • The force of the people pressing down on the track is equal to the force of the track pushing back up on the car.

• • The acceleration of the car is equal to the mass of the car and people divided by the velocity of the car.

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NGSS.HS-PS2-1

NGSS.HS-PS2-4

Part B

Which statement best supports the answer in Part A?

• • An object in motion always tends to remain in motion at a constant velocity.

• • Friction is a type of force that acts in opposition to the car's motion.

• • For every force, there is an equal and opposite force acting against it.

• • Speed, acceleration, and mass are used to calculate the velocity of an object.

Tags

NGSS.MS-PS2-2