Newton's third law Quiz

A box was placed at the top of a ramp and released. The free-body force diagram for the box as it moved down the ramp at a constant velocity is shown. Which two forces acting on the box have, according to Newton's third law, corresponding forces acting on the ramp?

• F and D

• F and R

• W and D

• W and R

A uniform solid cube is placed on a table. The diagram shows the forces acting on the table and on the cube. The dot at the start of every arrowed line indicates the point at which the force can be considered to act. Which of the following forces has been drawn in the wrong position?

• Rc

• Rt

• Wc

• Wt

Two forces make a Newton's third law pair. Which of the following statements is true for these forces?

• They act in different directions on the same body.

• They are the same type of force and act on different bodies.

• They have different magnitudes and act in different directions.

• They are the same type of force and have different magnitudes.

According to Newton's third law, when two objects interact they exert forces on each other. Which of the following statements is not a correct description of these forces?

• The forces act at the same time.

• The forces act in the same direction.

• The forces act on different objects.

• The forces have the same magnitude.

Two forces form a Newton's third law pair. Which of the following statements is not true?

• The forces act on the same object.

• The forces have the same magnitude.

• The forces act for the same time.

• The forces are the same type of force.

A person is pushing a trolley at a constant velocity. The floor exerts a force P on the person, the person exerts a force Q on the trolley. The trolley exerts a force R on the person and the total drag force on the trolley is S. Which pair of forces is a Newton's Third Law pair?

• P and R

• Q and R

• Q and S

• P and S

A massive star exerts a gravitational force Fstar on a small distant planet. The planet exerts a gravitational force Fplanet on the star. Which row of the table is correct?

• A

• B

• C

• D

A uniform solid cube is placed on a table. The diagram shows the forces acting on the table and on the cube. The table has four legs. Which of the following statements is correct according to Newton's third law?

• 4Rf = Rc + Rt

• 4Rf = Rc + Wt

• Rc = Rt

• Rt = Wc

A lift moves upwards from rest with an acceleration α. A student of mass 70 kg standing in the lift exerts a force of 800 N on the floor of the lift. Which of the following expressions could be used to determine α?

• 70g = 70α

• 800 = 70α

• 800 − 70g = 70α

• 70g − 800 = 70α

Once in orbit above the Earth's atmosphere, the engines on a space rocket are switched off. Which row of the table correctly states the resulting motion of the rocket and the law explaining this motion?

• A

• B

• C

• D