Forces

Question 1

What is a force?

Answer 1

A force is a push or a pull.

It is a vector quantity.

It is measured in Newtons.

Question 2

What are forces represented by?

Answer 2

Forces are represented using an arrow.

The length of the arrow represents the size of the force, and the arrowhead represents the direction.

Question 3

A longer arrow represents a…

Answer 3

larger force

Question 4

A shorter arrow represents a…

Answer 4

smaller force

Question 5

What are the two types of forces?

Answer 5

Non-contact forces and Contact Forces

Question 6

What are Contact Forces?

Answer 6

Contact forces need a physical contact to get created.

Question 7

What are examples of contact forces?

Answer 7

Friction, Tension, Normal Reaction Force, Upthrust (Buoyancy Force), Thrust.

Question 8

What are non-contact forces?

Answer 8

Non-contact forces get created due to fields (magnetic, electronic, gravitational).

Question 9

What are examples of non-contact forces?

Answer 9

Weight (Gravitational Force)
Magnetic Force
Electrostatic Force

Question 10

What’s normal reaction force?

Answer 10

When we keep an object on a surface, the weight of the object presses the surface down. The surface is giving a reaction on to the object according to Newton’s 3rd law.

Question 11

What is Newton’s third law?

Answer 11

For every action (force) in nature, there is an equal and opposite reaction.

Question 12

What is point of action?

Answer 12

Point of action of a force is from a point at the bottom of an object which is in contact with the surface.

Question 13

Normal reaction should always be marked…

Answer 13

perpendicular to the surface.

Question 14

What is friction?

Answer 14

Friction always opposes the motion. Frictional force always creates heat energy.

Question 15

Friction is marked along…

Answer 15

the surfaces which are in contact.

Question 16

Friction also gets created when…

Answer 16

an object is moving inside a fluid (liquid/gas)

Question 17

Friction inside fluids is also known as…

Answer 17

drag force/air resistance/ water resistance/viscous force

Question 18

What are examples of friction in fluids?

Answer 18

When a hot air balloon is acting up, so the air resistance is acting down.

When a parachutist is falling down, so the air resistance is acting up.

Question 19

What is tension?

Answer 19

Tension gets created when the object is being stretched. Tension acts inwards from the two ends of the object. It’s like a rope is pulling back the person who is pulling it.

Question 20

What is upthrust?

Answer 20

Upthrust acts upwards on an object that is fully/partially immersed in a fluid (gas or liquid).

Question 21

What is buoyancy point?

Answer 21

The point from which the upthrust is acting.

Question 22

Upthrust always acts…

Answer 22

vertically upwards.

Question 23

What is weight/gravitational force?

Answer 23

Weight is the force acting on an object due to gravity. Weight depends on gravitational field strength.

Question 24

Gravitational field strength…

Answer 24

is different on different planets. Higher the mass of the planet, higher the field strength.

Question 25

Gravitational field strength is also known as what?

Answer 25

Gravitational acceleration?

Question 26

What is the centre of gravity?

Answer 26

Weight always acts from the point known as the centre of gravity.

Question 27

Weight always acts in which direction?

Answer 27

Vertically down.

Question 28

What's the equation for Weight?

Answer 28

Weight = Mass * Gravitational Field Strength W = m * g

Question 29

What are the effects of forces on objects?

Answer 29

A force can change the speed, direction and the shape of an object.

Question 30

What is a resultant force?

Answer 30

A single force which can give the same effect as several forces added together.

Question 31

What is a balanced force?

Answer 31

If the resultant force on an object is 0, the object is said to be balanced.

Question 32

What should two forces have to be balanced?

Answer 32

The same magnitude, should act in opposite directions, and same line of action.

Question 33

What are unbalanced forces?

Answer 33

If there is a value for the resultant force, the forces are unbalanced. The amount of unbalanced force is equal to the resultant force.

Question 34

What is Newton's First Law?

Answer 34

When the forces on an object are balanced, the object will remain at rest or move with a constant velocity along a straight line.

Question 35

What does Newton's first law reveal?

Answer 35

It reveals that there are two situations when the forces on an object are balanced: -When they are at rest/stationary -When they are moving at a constant velocity.

Question 36

Unbalanced forces acting on an object cause it to...

Answer 36

accelerate/decelerate This means that the velocity of the object changes with time.

Question 37

What is Newton's 2nd Law?

Answer 37

Newton's second law states that the acceleration of an object is directly related to the net force and inversely related to its mass Therefore: f = m * a

Question 38

The magnitude of the object's acceleration is ...... to the magnitude of the resultant force.

Answer 38

directly proportional

Question 39

The magnitude of the object's acceleration is .... to the mass of the object.

Answer 39

inversely proportional

Question 40

Resultant force is measured in what?

Answer 40

Newtons (N)

Question 41

Acceleration is measured in?

Answer 41

m/s^2

Question 42

Mass is measured in...

Answer 42

kilograms

Question 43

What's the difference between mass and weight?

Answer 43

Mass is the amount of matter an object contains while weight is the force acting downwards on an object due to gravity.