P8- Forces in Balance

Question 1

What does a scalar quantity have?

Give some examples

Answer 1

A scalar quantity has magnitude.
Speed
Distance
Temperature

Question 2

What does a vector quantity have?

Give some examples

Answer 2

It has magnitude and direction.
Velocity
Displacement
Force

Question 3

What is a contact force?

Give some examples

Answer 3

A force which must touch another force for the force to act
Air resistance
Friction

Question 4

What is a non contact force?

Give some examples

Answer 4

A non contact force is a force which doesn’t need to touch another force to act.
Magnetic force
Gravitational force

Question 5

What is the difference between weight and mass?

Answer 5

Mass is just the amount of stuff in an object whereas weight is the force acting on an object due to gravity

Question 6

What is the formula for weight?

Answer 6

Weight = Mass x Gravitational field strength

Question 7

What is the resultant force?

Answer 7

The resultant force is the total force on a point or object

Question 8

What does a free body diagram do?

Answer 8

It shows you all the forces acting on an object

Question 9

What is the formula for work done?

Answer 9

Work done = Force x Distance

Question 10

What does it mean when an object is in equilibrium?

Answer 10

It means that the forces are balanced

Question 11

What is the formula for moment?

Answer 11

Moment = force x distance

Question 12

What do levers do?

Answer 12

They increase the distance from the pivot

Question 13

What is displacement?

Answer 13

1) Displacement is distance in a given direction.

Question 14

What does Newton’s thrid law state?

Answer 14

1) Newton’s 3rd law states that when 2 objects interact, they always exert equak and opposite forces on eachother.

Question 15

Explain what a contact force is.

Answer 15

1) A contact force is a force that acts on objects only when the objects touch eachother.

Question 16

Explain what driving force and how friction helps a car move along the road.

Answer 16

1) The driving force on a car is the force that makes the car move.
2) The driving force pushes the car forward because there is frction between the ground and the tyre of each drive wheel. Friction acts when the tyre is in contact with the ground.

Question 17

Explain what happens when a car moves foward

Answer 17

When a car moves forward:
1) The force of the friction of the road on the tyre is in the forward direction.
2) The force of the friction of the tyre on the road is in the reverse direction.
These 2 forces are equal and opposite to eachother.

Question 18

What is the resultant force of an object?
What happens to objects when:
Their reusltant force is zero
Their resultant force is greater than 0.

Answer 18

1) The resultant force of an object is a single force that has the same effect as all the forces acting on an object.
2) When an objects resultant force equals zero, the object stays at rest or at the same speed and direction. When the resultant force of an object is greater than zero, then the speed or direction of that object will change.

Question 19

What happens if two forces act on an object along the same line (to do with resultant force)

Answer 19

1) The resultant force is their sum if the forces act in the same direction.
2) Their difference if the forces act in opposite directions

Question 20

Explain what the moment of a force is.

How can you increase the moment of the force of an object?

Answer 20

1) The moment of a force is a measure of the turning effect of the force on an object.
2) Increasing the size of the force, using a spanner with a longer handle.

Question 21

Wha are gears used for?

Answer 21

1) Gears are used to change the moment of a turning effect.

Question 22

Explain what hapens when a low gear in a car is chosen.

Answer 22

1) A small gear wheel driven by the engine shaft is used to turn a large gear wheel on an output shaft. So the output shaft turns slower than the engine shaft.
2) The turning effect of the output shaft is greater than the turning effect of the engine shaft.

Question 23

Explin what happens when a high gear in a car is chosen.

Answer 23

1) A large gear wheel driven by thhe engine shaft is used to turn a small gear wheel on the output shaft. So the output shaft turns faster than the engine shaft, so the car can move at a higher speed.
2) But the force of the smaller gear wheel acts nearer to its shaft than the force of the larger gear wheel acting on its shaft. So the turning effect of the output shaft is less than the turning effect of the engine shaft.