Forces

Question 1

What is the difference between a scalar quantity and a vector quantity?


Answer 1

A scalar quantity is just a number, while a vector quantity includes both magnitude and a direction.

Question 2

Give an example of a scalar quantity:

Answer 2

• Distance
• speed
• mass
• temperature
• time

Question 3

Give an example of a vector quantity:

Answer 3

• Displacement
• force
• velocity
• acceleration
• momentum

Question 4

How is weight defined in relation to mass?


Answer 4

Weight is defined as mass multiplied by the gravitational field strength.

Question 5

What units are used to measure weight?


Answer 5

Newtons

Question 6

What units are used to measure mass?

Answer 6

Kilograms

Question 7

What are the units for work?


Answer 7

Joules

Question 8

What is Hooke’s Law?


Answer 8

Hooke’s Law states that the force exerted by a spring is directly proportional to its extension.
Formula: Force = Spring Constant × Extension
Valid until the limit of proportionality is reached.

Question 9

What is the formula for Hooke’s Law?


Answer 9

Force = Spring Constant × Extension

Question 10

What is the unit for spring constant?


Answer 10

Newtons per meter

Question 11

What does the moment of a force refer to?


Answer 11

The moment of a force refers to the turning effect produced by a force acting at a distance from a pivot point.

Question 12

What is the formula for moment?


Answer 12

Moment = Force × Distance

Question 13

What are the units for moment?


Answer 13

Newton meters

Question 14

What are the units for pressure?


Answer 14

Pascals

Question 15

What is the value of gravitational field strength on Earth?


Answer 15

9.8 Newtons per kilogram

Question 16

What are the units for distance

Answer 16

Meters (m)

Question 17

What does a slope on a distance-time graph indicate?


Answer 17

An increasing slope indicates movement, and the steeper the slope, the faster the movement.

Question 18

How can speed be calculated from a distance-time graph?

Answer 18

Speed can be calculated as the gradient of the graph, which is distance over time.

Question 19

What does a velocity-time graph show?


Answer 19

A velocity-time graph shows how velocity changes over time, with acceleration represented by the gradient.

Question 20

What does the area under a velocity-time graph represent?


Answer 20

The area under a velocity-time graph represents the distance traveled.

Question 21

What is terminal velocity?


Answer 21

Terminal velocity is the constant speed reached when the force of gravity is balanced by the drag force.

Question 22

What principles does a Newton’s Cradle demonstrate?


Answer 22

Inertia: An object in motion stays in motion unless acted upon by an external force.
Conservation of energy: Energy is never created or destroyed, only transformed.
Newton’s third law: For every action, there is an equal and opposite reaction.

Question 23

What is thinking distance?


Answer 23

Thinking distance is the distance traveled while a driver reacts to a stimulus.

Question 24

What factors can affect thinking distance?


Answer 24

Alcohol, drugs, and fatigue can negatively affect thinking distance, while caffeine can positively affect it.

Question 25

What are the units for momentum?


Answer 25

Kilogram meters per second

Question 26

What does the law of conservation of momentum state?


Answer 26

The law of conservation of momentum states that momentum before a collision equals momentum after a collision.

Question 27

how does an object reach equilibrium?

Answer 27

By having the forces on it balanced

Question 28

describe a force:

Answer 28

a force is a push or pull on an object that is caused by it interacting with something. It can be contact or non-contact

Question 29

give an example of a contact force:

Answer 29

• friction
• air resistance
• tension in ropes
• normal contact force

Question 30

give an example of a non-contact force:

Answer 30

• magnetic force
• gravitational force
• electrostatic force

Question 31

what is a resultant force?

Answer 31

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

Question 32

what is extension directly proportional to?

Answer 32

the extension of a stretched spring is directly proportional to the load or force applied
F = ke

Question 33

what is a moment in relation to forces?

Answer 33

A force, or several forces, can cause an object to rotate. The turning effect of a force is called its moment. The size of the moment of the force is:
M = Fd

Question 34

What are levers used for?

Answer 34

levers increase the distance from the pivot at which the force is applied. This means less force is needed to get the same moment, so levers make it easier to do work - like lift a load

Question 35

what are gears and why do we use them?

Answer 35

• gears are circular discs with “teeth” around the edges. The teeth interlock so that turning one will cause the next to turn in the opposite direction. They are used to transmit the rotational effect of a force from one place to another.

Question 36

what is pressure?

Answer 36

pressure is the force per unit area.

Question 37

what does pressure in a liquid depend on?

Answer 37

• the density - density is the compactness of a substance
• depth - the height of the container

Question 38

what happens if an object is submerged in a liquid?

Answer 38

the pressure of the fluid exerts a force on it from every direction. Pressure increases with depth, therefore the force on the bottom is larger than the force exerted on the top. This causes a resultant force upwards - Upthrust

Question 39

why does an object float in a liquid?

Answer 39

If the upthrust on an object is equal to the object’s weight, then the forces balance and the object floats.

Question 40

You need to know the following speeds:
- A person walking?
- A person running?
- A person cycling?
- A car?
- A train?
- A plane?

Answer 40

• A person walking = 1.5 m/s
• A person running = 3 m/s
• A person cycling = 6 m/s
• A car = 25 m/s
• A train = 55 m/s
• A plane = 250 m/s

Question 41

What is distance and displacement?

Answer 41

• distance is how far an object has moved, it is a scalar quantity so it does not involve direction
• displacement is the distance and direction in a straight line from an objects starting point to its finishing point, it is a vector quantity

Question 42

what does speed and velocity measure?

Answer 42

speed and velocity both measure how fast you’re going, but speed is a scalar quantity, and velocity is a vector quantity:
speed - how fast something moves
velocity - speed in a given direction

Question 43

what is acceleration and uniform acceleration?

Answer 43

• acceleration is how quickly you are speeding up (the change in velocity in an amount of time)
• uniform acceleration is a constant acceleration

Question 44

what is friction?

Answer 44

friction is always there to slow things down. If an object has no force propelling it along it will always slow down and stop due to friction (unless in space where there is nothing to rub against).

Question 45

what is drag in terms of forces?

Answer 45

drag is the resistance you get in a fluid (liquid or gas). As speed decreases, drag increases.

Question 46

what is terminal velocity?

Answer 46

It is the maximum speed that an object falling through a fluid reaches, it will reach it then fall at a steady speed

Question 47

what is inertia?

Answer 47

An object in motion stays in motion unless acted upon by an external force.

Question 48

what is Newton’s third law?

Answer 48

For every action, there is an equal and opposite reaction.