Forces

Question 1

What is the resultant force?

Answer 1

The resultant force is the sum of all of the forces acting on an object.

The change in an object’s motion is caused by the resultant force.

Question 2

What does it mean when a resultant force is acting on the object?

Answer 2

If the forces acting on an object are unbalanced (not equal), it means that a resultant force is acting on the object.

Question 3

Resultant force equation

Answer 3

Resultant force (F) = mass (m) x acceleration (a)
F=ma

Question 4

What will happen to a moving object if there is no resultant force?

Answer 4

It will continue to move at a constant velocity

Question 5

What is newtons law?

Answer 5

Newton’s 1st Law says that the velocity of an object will only change if a resultant force is acting on the object. This applies to a stationary (still) or moving object.

Question 6

True or false

If an object is stationary (not moving) and there is no resultant force acting on it, it will stay stationary.

Answer 6

True

Question 7

True or false

Answer 7

If an object is moving and there is no resultant force acting on it, the object will continue moving in the same direction at the same speed.

This means the object will continue moving at the same velocity

Question 8

What is the resultant force on a stationary object?

Answer 8

None

Question 9

What is the definition of the resultant force?

Answer 9

The resultant force is the sum of all the forces acting on an object

Question 10

What is newtons 3rd law?

Answer 10

Newton’s Third Law says that: whenever 2 objects interact, the forces that they exert on (apply to) each other are equal and opposite.

Question 11

Which of Newton’s laws states that when objects interact, the forces they exert on (apply to) each other are equal and opposite?

Answer 11

Third law

Question 12

What are free body force diagrams?

Answer 12

A free body force diagram is a diagram showing the forces acting on an object. These are shown as vectors.

Question 13

What are the forces acting on a skydiver?

Answer 13

The forces acting on a skydiver are air resistance (acting upwards) and the skydiver’s weight (acting downwards).

Question 14

What are the forces acting on a driving car?

Answer 14

The forces acting on a driving car are the driving force, the normal contact force, the weight and friction.

Question 15

Why do we use free body diagrams?

Answer 15

We can use free body diagrams to work out the resultant force when more than one force is acting on an object. We can also use the diagrams to see if an object is in equilibrium. If the resultant force is zero, we say the object is in equilibrium.

Question 16

True or false
We can use free body diagrams to work out the resultant force when more than one force is acting on an object. We can also use the diagrams to see if an object is in equilibrium. If the resultant force is zero, we say the object is in equilibrium.

Answer 16

True

Question 17

Can you use a vector diagram to work out the resultant force when 2 other forces of given?

Answer 17

Yes

Question 18

What forces act on a cliff diver?

Answer 18

Air resistance, divers weight

Question 19

Can you bend, stretch and compress objects by applying forces to them?

Answer 19

Yes - for this to happen there must be 2 or more forces acting on the object

Question 20

At least how many forces must be acting on an object to stretch, bend or compress it?

Answer 20

2

Question 21

What is the 2 ways objects can be deformed?

Answer 21

Elastically and inelastically

Question 22

An elastically deformed object will return to its original shape when the force stops.

Answer 22

True

Question 23

Inelastic deformation

Answer 23

An inelastically deformed object will not return to its original shape when the force stops.

Question 24

At least how many forces must be acting on an object to stretch, bend or compress it?

Answer 24

2

Question 25

In the context of springs, what is extension?

Answer 25

The change in length of a spring when a force is applied

Question 26

Force equation

Answer 26

Force = spring constant x extension

Question 27

How do you investigate hooked law?

Answer 27

First, measure the original length of the spring.
Next, hang different masses on the spring and measure the length of the spring in each case.
Adding masses to the spring increases the downwards force as each mass has weight.
The extension of the spring equals the length with masses minus the original length:
extension of the spring = length of the spring with masses − original length of the spring.
Plot a graph with the extension of the spring on the x-axis and force on the y-axis.

Question 28

Which law relates the force and extension of a stretched spring?

Answer 28

Hooked law

Question 29

Equation for Spring Extension

Answer 29

Extension = length of loaded spring - natural length of spring