Force and Motion

A student is sitting still on a swing at the playground. He asks his friend to give him a push. She walks behind him and pushes him forward, and he begins swinging back and forth. When did the student experience unbalanced forces?

• when he sat on the swing without moving

  The student experienced balanced, not unbalanced, forces when he sat on the swing without moving.

• when he was pushed forward by his friend

  His friend pushed him with a greater force than was acting on him when he was sitting still, so the forces acting on him became unbalanced.

• when the forces acting on him were equal from each side

  The student experienced balanced, not unbalanced, forces when they were equal from each side.

• when the forces acting on him were equal from above and below

  The student experienced balanced, not unbalanced, forces when they were equal from above and below.

Tags

NGSS.MS-PS2-2

Which statement BEST describes the motion of the box when the forces pull on the box?

• The box will move to the left because the forces are balanced.

  The forces on the box are unbalanced, not balanced. 

• The box will move to the right because the forces are balanced.

  The box will move to the left, not right, because the pulling force is more on the left. So, the forces are unbalanced, not balanced.

• The box will move to the left because the forces are unbalanced.

  The box will move to the left because the pulling force is more on the left.

• The box will move to the right because the forces are unbalanced.

  The box will move to the left, not right. 

Tags

NGSS.MS-PS2-2

Which of the following is an example of unbalanced forces?

• a soccer ball sitting on a field.

• a hanger hanging on a rod

• a ball thrown up that comes back down.

• a parked bus.

Tags

NGSS.MS-PS2-2

A water rocket uses an amount of water and pressurized air to send a plastic rocket several feet into the air. As the water and air rush out the tail end of the rocket, the rocket shoots into the air. 

Which statement explains the rocket's motion?

• The inertia of the water and air must be overcome. 

  This answer is the result of a misunderstanding of Newton's laws. Inertia must be overcome, but this does not explain the motion of the rocket. 

• The force of gravity of the rocket is greater than the water. 

  This answer is the result of a misunderstanding of Newton's laws. The force of gravity of the rocket is not greater than the water and this does not explain the motion of the rocket. 

• The force of gravity must be overcome to achieve lift.  

  This answer is the result of a misunderstanding of Newton's laws. The force of gravity must be overcome, but this does not explain the motion of the rocket.

• For every action there is an equal and opposite reaction.

  This answer is correct. Newton's third law explains the rocket's motion. 

Max is helping his parents move to a new house. He picks up one box and is able to carry it into the house. He tries to pick up a second box with an identical volume, but he is unable to lift it. What is most likely the difference between the two boxes?

• The box Max can lift has more mass and requires less force to lift.

• The box Max can lift has more mass and requires less friction to lift.

• The box Max cannot lift has more mass and requires more force to lift.

• The box Max cannot lift has more mass and requires more friction to lift.

Tags

NGSS.MS-PS2-2

NGSS.MS-PS2-4

An object at rest remains at rest. An object in motion remains in motion unless acted upon by an outside force. This describes Newton's

• first law of motion.

• second law of motion.

• third law of motion.

• first and third laws of motion.

An airplane is flying at 80 kilometers per hour when a strong tail wind, traveling in the same direction at 5 kilometers per hour, hits the airplane. How can the net force acting on the airplane be calculated?

• add the forces.

• subtract the forces.

• multiply the forces.

• divide the forces.

Tags

NGSS.MS-PS2-2

Which of the following causes people in a moving car to continue moving forward, even when the car stops?

• inertia

• gravity

• friction

• tension

According to Newton's second law, what happens when the same force is applied to two objects of different masses?

• The object with greater mass will experience a smaller acceleration.

  The object with the greater mass will experience a smaller acceleration when the same force is applied to both masses. 

• The object with greater mass will experience a greater acceleration.

  The object with the greater mass will experience a smaller, not greater, acceleration when the same force is applied to both masses. 

• The object with smaller mass will experience a smaller acceleration.

  The object with the greater, not smaller, mass will experience a smaller acceleration when the same force is applied to both masses. 

• The two objects experience the same acceleration.

  The object with the greater, not smaller, mass will experience a smaller, not the same, acceleration when the same force is applied to both masses.

Tags

NGSS.MS-PS2-2

Why do the values on the graph form a straight line?

• The speed is constant.

• The distance remains unchanged.

• The direction of the motion stays the same.

• The speed gradually increases over time.

Tags

NGSS.MS-PS3-1