Interpret force diagrams and sums of forces

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Middle School Physical Science › Interpret force diagrams and sums of forces

Questions 1 - 10
1

Screen shot 2020 05 26 at 5.16.57 pm

What is the net force acting on this object?

0 Newtons

1000 Newtons

1,400 Newtons

400 Newtons

Explanation

The answer is "0 Newtons" because all the forces are balanced.

When we make diagrams or drawings of forces, we use vectors. A vector is an arrow that represents the magnitude and the direction of a force. The magnitude is how strong the force is, usually in Newtons, and the direction can be expressed in north, south, east, west, left, right, up, or down.

In order to evaluate the sum of forces in a free body diagram you have to add the vectors of forces both in the horizontal and in the vertical direction. The sum of forces in all directions is called the “net force.” When forces are going in opposite directions, they should be subtracted or the value of one of the forces should be given a negative to account for the direction.

2

A soccer ball is kicked on the ground with 100 Newtons of force to the right. The ball never leaves the ground. What is the net force acting in the upwards and downwards direction?

The net force in the upwards and downwards direction is zero.

The net force in the upwards and downwards direction is 100 Newtons.

The net force in the upwards and downwards direction is 50 Newtons.

The net force in the upwards and downwards direction is 25 Newtons.

Explanation

The answer is "The net force in the upwards and downwards direction is zero."

When we make diagrams or drawings of forces, we use vectors. A vector is an arrow that represents the magnitude and the direction of a force. The magnitude is how strong the force is, usually in Newtons, and the direction can be expressed in north, south, east, west, left, right, up, or down.

In order to evaluate the sum of forces in a free body diagram you have to add the vectors of forces both in the horizontal and in the vertical direction. The sum of forces in all directions is called the “net force.” When forces are going in opposite directions, they should be subtracted or the value of one of the forces should be given a negative to account for the direction.

3

A box is falling from the sky and moving straight down with a force of 18,000 Newtons. What is the net force acting on the object?

18,000 Newtons downward

9,000 Newtons right and 9,000 Newtons downward

The net force is 0 because the box is falling and the forces are balanced

9,800 Newtons downward and the rest in the other directions because acceleration due to gravity is 9.8

Explanation

The answer is 18,000 Newtons because there is no normal force acting on the object in the upward direction if there is no surface below it.

When we make diagrams or drawings of forces, we use vectors. A vector is an arrow that represents the magnitude and the direction of a force. The magnitude is how strong the force is, usually in Newtons, and the direction can be expressed in north, south, east, west, left, right, up, or down.

In order to evaluate the sum of forces in a free body diagram you have to add the vectors of forces both in the horizontal and in the vertical direction. The sum of forces in all directions is called the “net force.” When forces are going in opposite directions, they should be subtracted or the value of one of the forces should be given a negative to account for the direction.

4

Screen shot 2020 05 22 at 2.43.54 pm

The image above shows an object being pushed with a force, and the sum of forces in both directions. Why are some of the forces in this diagram negative?

Some of the forces are negative because they're going different directions.

Some of the forces are negative because they're "pulls" not "pushes".

Some of the forces are negative because they're "pushes" not "pulls".

None of these

Explanation

The answer is "Some of the forces are negative because they're going different directions."

When we make diagrams or drawings of forces, we use vectors. A vector is an arrow that represents the magnitude and the direction of a force. The magnitude is how strong the force is, usually in Newtons, and the direction can be expressed in north, south, east, west, left, right, up, or down.

In order to evaluate the sum of forces in a free body diagram you have to add the vectors of forces both in the horizontal and in the vertical direction. The sum of forces in all directions is called the “net force.” When forces are going in opposite directions, they should be subtracted or the value of one of the forces should be given a negative to account for the direction.

5

Screen shot 2020 05 22 at 2.59.47 pm

What is the net force acting on this object?

1,002 N to the right

3,710 N to the left

3,710 N to the right

the net force is 0 N

Explanation

The answer is "1,002 N to the right" because the up and down forces are balanced, and the force acting towards the left is 1,0002 N stronger than the force acting to the right

6

Screen shot 2020 05 22 at 3.02.58 pm

Describe the motion of this cylinder.

It is moving to the right with a force of 500 Newtons.

It is not moving because the two forces cancel out and equal 0 Newtons.

It is moving to the right and down with a force of 500 Newtons.

It is not moving with a force of 500 Newtons.

Explanation

The answer is "It is moving to the right with a force of 500 Newtons," because the two 250 N forces are going the same direction and thus added together.

When we make diagrams or drawings of forces, we use vectors. A VECTOR is an arrow that represents the MAGNITUDE and the DIRECTION of a force. The magnitude is how strong the force is, usually in Newtons, and the direction can be expressed in north, south, east, west, left, right, up, or down.

In order to evaluate the sum of forces in a free body diagram you have to add the vectors of forces both in the horizontal and in the vertical direction. The sum of forces in all directions is called the “net force.” When forces are going in opposite directions, they should be subtracted or the value of one of the forces should be given a negative to account for the direction.

7

Two people are pushing on an object. One person pushes the object 20 Newtons to the right. The other person pushes the object 50 Newtons to the left. What is the net force on the object?

30 newtons to the left

50 newtons to the left

80 newtons

0 newtons

Explanation

The answer is 30 Newtons to the left.

When we make diagrams or drawings of forces, we use vectors. A vector is an arrow that represents the magnitude and the direction of a force. The magnitude is how strong the force is, usually in Newtons, and the direction can be expressed in north, south, east, west, left, right, up, or down.

In order to evaluate the sum of forces in a free body diagram you have to add the vectors of forces both in the horizontal and in the vertical direction. The sum of forces in all directions is called the “net force.” When forces are going in opposite directions, they should be subtracted or the value of one of the forces should be given a negative to account for the direction.

8

Screen shot 2020 05 22 at 2.44.06 pm

What is the net force acting on this object?

500 N left

900 N left

500 N left, 200 N down

100 N

Explanation

The answer is "500 N left" because the upwards and downwards forces are balanced, and the leftward force is 500N.

When we make diagrams or drawings of forces, we use vectors. A vector is an arrow that represents the magnitude and the direction of a force. The magnitude is how strong the force is, usually in Newtons, and the direction can be expressed in north, south, east, west, left, right, up, or down.

In order to evaluate the sum of forces in a free body diagram you have to add the vectors of forces both in the horizontal and in the vertical direction. The sum of forces in all directions is called the “net force.” When forces are going in opposite directions, they should be subtracted or the value of one of the forces should be given a negative to account for the direction.

9

Screen shot 2020 05 22 at 2.44.15 pm

Are the forces in this image balanced or unbalanced, and how is the object moving?

unbalanced and the object is moving left with a force of 50 Newtons

unbalanced and the object is moving right with a force of 50 Newtons

balanced and the object is moving right with a force of 50 Newtons

balanced and the object is moving left with a force of 50 Newtons

Explanation

The answer is "unbalanced, the object is moving left with a force of 50 Newtons." The object is moving because the forces are unbalanced, and the net force is 50 Newtons to the left because the magnitude of that force is 50 Newtons stronger than the one going right.

When we make diagrams or drawings of forces, we use vectors. A vector is an arrow that represents the magnitude and the direction of a force. The magnitude is how strong the force is, usually in Newtons, and the direction can be expressed in north, south, east, west, left, right, up, or down.

In order to evaluate the sum of forces in a free body diagram you have to add the vectors of forces both in the horizontal and in the vertical direction. The sum of forces in all directions is called the “net force.” When forces are going in opposite directions, they should be subtracted or the value of one of the forces should be given a negative to account for the direction.

10

True or false: A book sitting still on a table has no forces acting on it.

False

True

Explanation

The answer is false. The book has forces acting on it but the net force is 0.

When we make diagrams or drawings of forces, we use vectors. A vector is an arrow that represents the magnitude and the direction of a force. The magnitude is how strong the force is, usually in Newtons, and the direction can be expressed in north, south, east, west, left, right, up, or down.

In order to evaluate the sum of forces in a free body diagram you have to add the vectors of forces both in the horizontal and in the vertical direction. The sum of forces in all directions is called the “net force.” When forces are going in opposite directions, they should be subtracted or the value of one of the forces should be given a negative to account for the direction.

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