Forces and Energy

Forces and Energy

By Katie Heter

​tug of war

​The blue and red person are playing tug of war, trying to get the bucket of candy. What force are they using?

Multiple Choice

What force is the blue person using?

• 50

• 100

• 150

• 200

Multiple Choice

What force is the red person using?

• 50

• 100

• 150

• 200

Multiple Choice

What is the sum of the forces?

• 50 to the right

• 50 to the left

• 150 to the left

• 100 to the right

Multiple Choice

Who will win tug of war?

• Red Person

• Blue Person

Multiple Choice

What is the force being exerted by the blue person?

• 50

• 100

• 150

• 200

Multiple Choice

What is the force being exerted by the red person?

• 50

• 100

• 150

• 200

Multiple Choice

What is the sum of forces?

• 50 to the right

• 50 to the left

• 150 total

• 100 to the right

Multiple Choice

Who would win at tug of war?

• Blue Person

• Red Person

Multiple Choice

What force are the two blue people applying to the cart together?

• 50

• 100

• 200

• 0

Multiple Choice

What force is the red person applying to the cart?

• 50

• 100

• 200

• 0

Multiple Choice

If the two blue and one red person are pulling the cart which way will it move?

• left

• right

• it will stay still

• 0

Multiple Choice

Are the forces in this scenario balanced or unbalanced?

• balanced

• unbalanced

Multiple Choice

How do you know?

• THe small people are pulling 50 N to the left

• The medium person is pulling at 100N

• The net force is 0N

• The right force is 100N

Multiple Choice

Which direction will the cart move?

• left

• right

• neither

Multiple Choice

Are the force balanced or unbalanced?

• balanced

• unbalanced

Multiple Choice

What would happen to the speed of the cart when one side is winning tug of war?

• it doesn't change

• it decreases

• it increases

Multiple Choice

What would happen to the speed of the cart when the tug of war is a tie?

• it doesn't change

• it decreases

• it increases

Multiple Choice

When 2 small figures are both pulling in the same direction, their individual force must be

• added

• subtracted

• multiplied

• divided

Multiple Choice

When 2 small figures are both pulling in opposite directions, their individual force must be

• added

• subtracted

• multiplied

• divided

Multiple Choice

A balanced force results when the sum of all forces is _____ and does not cause an object to move.

• greater than 1

• zero

• less than 1

Multiple Choice

An unbalanced force results when the sum of all forces is not zero and causes the object to

• stay still

• move or change direction

• go to sleep

• eat candy

Multiple Choice

Is the box in motion?

• yes

• no

Multiple Choice

In which direction and with what force is the box moving?

• 0 N

• 40 N to the Left

• 20 N to the Right

• 20 N to the Left

Distance vs Time Graphs

A distance-time graph shows how the distance and speed of an object changes with time. This graph shows the movement of three objects over time. The slope, or steepness, of each line indicates the object's rate of speed. In general, the steeper the slope, the faster the object's speed.

Multiple Choice

Match the photo with the scenario it best represents.

• running at a steady pace away from starting line

• running at a steady pace back to the starting line

• accelerating away from the starting line

• standing still

Multiple Choice

Match the photo with the scenario it best represents.

• running at a steady pace away from starting line

• running at a steady pace back to the starting line

• accelerating away from the starting line

• standing still

Multiple Choice

Match the photo with the scenario it best represents.

• running at a steady pace away from starting line

• running at a steady pace back to the starting line

• accelerating away from the starting line

• standing still

Multiple Choice

One graph shows a runner accelerating or getting faster as the run goes on, the other shows deceleration, or getting slower as the run goes on. Which graph is which?

• D= Acceleration E=Deceleration

• D=Deceleration E=Acceleration

Velocity vs Time

In a velocity-time graph, acceleration is represented by the slope, or steepness, of the graph line.

​

Velocity vs Time

​

If the line slopes upward, like the line between 0 and 4 seconds, velocity is increasing, so acceleration is positive.

If the line is horizontal, as it is between 4 and 7 seconds, velocity is constant and acceleration is zero.f

Velocity vs Time

​

​

If the line is horizontal, as it is between 4 and 7 seconds, velocity is constant and acceleration is zero.

Velocity vs Time

​

​

If the line slopes downward, like the line between 7 and 10 seconds, velocity is decreasing and acceleration is negative.

Negative acceleration is called deceleration.

Multiple Choice

A flat line on a distance time graph represents an object staying still. What does a flat line represent on a velocity/speed vs time graph?

• Steady Movement

• Slowing Down

• Speeding Up

• Stopping

Multiple Choice

Which scenario would be reasonable for the above velocity vs time graph?

• A car slows down, stops at a light, then accelerates away.

• A car speeds up, stops for a railroad then, accelerates away.

• A car speeds up, goes a steady speed then slows down for a light.

• A car speeds up and then slows down for a light.

Open Ended

Why would it be important to check the labels on a graph to see if it is velocity vs time or distance vs time before answering the questions?

Multiple Choice

6. The diagram below shows forces acting on a model airplane. Both its speed and height above the ground are constant. Which of the following conditions would cause the model airplane to descend toward the ground?

• The lift is equal to the drag.

• The lift is less than the weight.

• The thrust is equal to the weight.

• The thrust is greater than the drag.

Multiple Choice

7. The graph below represents the time and distance traveled by four different toy cars. Which object had the greater average speed?

• Object A

• Object B

• Object C

• Object D

Multiple Choice

8. An object moves through space with balanced forces acting on it. Which statement best describes the speed and

direction of the object as long as the forces acting on it remain balanced?

• The sped and direction of the object will both change.

• The speed and direction of the object will remain constant.

• The speed will change, but the direction will remain constant.

• The speed will remain constant, but the direction will change.

Multiple Choice

9. The displacement-time graph below represents the motion of a cart initially moving forward along a straight line. During which interval is the cart moving forward at a constant speed?

• AB

• DE

• CD

• BC

Multiple Choice

10. The displacement-time graph below represents the motion of a cart initially moving forward along a straight line. During which interval is the cart stationary?

• AB

• DE

• CD

• BC

Multiple Choice

12. What happens when the forces applied to an object at rest produce a net force of zero?

• The object will move at a constant speed.

• The object will have a positive acceleration.

• The object will have a negative acceleration

• The object will not move at all.

Multiple Choice

13. A scientist created the graph below of the motion of three objects. Which of the following is correct about the motion of the objects?

• Object Q is not moving at all.

• Object S is traveling at a faster speed than Object R.

• Object R is increasing in speed by 2 m/s.

• Object R is traveling at a slower speed than Object S.

Multiple Choice

14. The unusual strength of a glue makes it able to hold a heavy object, or load, as show in the diagram. If the load exerts a strong downward force, the glue -

• destroys the force

• exerts a stronger downward force

• causes the load to accelerate upward

• exerts an upward force equal to the downward force