Topic 2 Experience 2 Calculating Forces Review

According to Newton's Third Law of Motion, for every action, there is an equal and opposite reaction.

Consider the following scenarios. 

 

Select the TWO scenarios that include a pair of forces that are equal in magnitude and opposite in direction.

• A person pushes a wall with a force of 50 N, the wall pushes back on the person with an equal force of 50 N in the same direction.

• A book exerts a 10 N force downward on a table due to gravity, and the table exerts an equal and opposite force of 10N upward on the book.

• A bat hits the ball with 100 N of force, the ball exerts an equal and opposite force of 100 N on the bat.

• A swimmer pushes the water backward with a force, the water pushes backward on the swimmer with an equal and opposite force.

• A bat hits the ball with 100 N of force, the ball exerts an equal and opposite force of 100 N on the bat.

Tags

NGSS.MS-PS2-1

A box is acted upon by two forces from opposite directions. What is the net force applied to the box?

• 10N

• 20N

• 30N

• 40N

Tags

NGSS.MS-PS2-1

NGSS.MS-PS2-2

Choose the answers that best describe what is happening in the image.  Choose 2 answers.

• The forces are balanced.

• The forces are unbalanced.

• The system is moving

• The system is not moving

Tags

NGSS.MS-PS2-1

NGSS.MS-PS2-2

According to Newton’s Third Law, what happens when a swimmer pushes against the pool wall to propel themselves forward?

• The wall pushes back against the swimmer with the same amount of force.

• The wall pushes back against the swimmer with twice as much force.

• The wall pushes back against the swimmer with half as much force

• The wall does not push back against the swimmer; the force of the swimmer’s push is what propels them forward.

Tags

NGSS.MS-PS2-1

What is the net force and direction of the force for the free-body diagram?

 ​ Fnet=​ (a)   Direction: ​ (b)  

• 20N
• 30N
• 120N
• 100N
• left
• right
• up
• down

Tags

NGSS.MS-PS2-2

Action forces and reaction forces always occur together.  Which of the following is an example of an action-reaction force pair?

• A swimmer pushes the water backward and the water flows over the swimmer.

• A bird flies by moving their wings and the feathers move in the wind.

• he tires on a car push against the road and the road pushes back on the tires.

• A person is pushing on a rock and the rock does not move.

Two students approach a motionless cart. The students push the cart in opposite directions. What is the BEST description of the forces at work on the cart?

• The forces are balanced

• The forces are equal and opposite.

• The forces are unequal and moving in the same direction

• The forces can cause the cart to move.

Tags

NGSS.MS-PS2-1

NGSS.MS-PS2-2

Describe the motion of the cart in the picture.

• The cart does not move because the students are pushing in opposite directions.

• Because the forces are opposite but unequal, the cart will move to the right and then to the left.

• The cart will move to the right and then stop.The force of the left pointing arrow will stop the cart's motion.

• The cart will move to the right; the forces are unbalanced with the greater force shown on the arrow pointing right.

Tags

NGSS.MS-PS2-2

When you push a wall with your hand, according to Newton's Third Law of Motion, what happens?

• The wall pushes back with a greater force. 

• 
  The wall does not push back. 

• The wall pushes back with the same amount of force.

• The wall moves in the same direction as your hand.

Which of the following is NOT an example of simultaneous force pairs that are equal in magnitude and opposite in direction that result from the interactions between objects using Newton's Third Law of Motion. 

• Pushing a shopping cart on a grocery store floor

• Launching a rocket

• Sliding an object on a surface with no friction 

• Bouncing a ball on the sidewalk

Tags

NGSS.MS-PS2-1