Resultant forces and work done

Question 1

How do free body diagrams show all the forces acting on an isolated object or a system?

Answer 1

1. The sizes of the arrows shows the relative magnitudes of the forces.
2. The direction of the arrows show the directions of the forcing acting on the object.

Question 2

What is a resultant force ?

Answer 2

A resultant force is the overall force on a point or object.

Question 3

If you have a number of forces acting at a single point what can you do ?

Answer 3

Replace them with a single force. ( as long as the single force has the same effect as all the original forces together)

Question 4

What is this single force called ?

Answer 4

The resultant force.

Question 5

If forces act along the same line what are they ?

Answer 5

Parallel

Question 6

How is the overall effect found ?

Answer 6

By adding the forces going in the same direction and subtracting the forces going in the opposite direction.

Question 7

If a resultant force moves an object what happens ?

Answer 7

Work is done.

Question 8

What happens when a force moves an object through a distance?

Answer 8

Energy is transferred and work is done.

Question 9

How do you make something move ( or keep moving is there are frictional forces) ?

Answer 9

Applying a force

Question 10

What must the thing applying force to make something move need ?

Answer 10

A source of energy ( like fuel or food)

Question 11

What does the force do to move the object and what is transferred from one store to another when it is done?

Answer 11

The force does ‘work’ to love the object and energy is transferred from one store to another.

Question 12

Wethere energy is transferred usefully or is wasted what is still
happening ?

Answer 12

Work is done.

Work done and energy transferred are the same thing.

Question 13

What is an example of this ?

Answer 13

When you push something along a rough surface ( like carpet) you are doing work against frictional forces. Energy is being transferred to the kinetic energy store if the object because it starts moving, but some is also being transferred to thermal energy stores due to friction. This causes the overall
temperature of the object to increase .

Question 14

What equation do you use to find out how much work is being done ?

Answer 14

Work done (J) = Force ( N ) x Distance ( moves along the line of action of the
force) ( m )

W = Fs