Forces

Question 1

Define a newton

Answer 1

Force causing 1kg of mass to accelerate 1ms⁻²

Question 2

Define density

Answer 2

Mass per unit volume of a substance

Question 3

Define pressure

Answer 3

The force exerted per unit cross sectional area

Question 4

Define pascal

Answer 4

Is 1 newton per square meter

Question 5

Define torque of a couple

Answer 5

The turning effect of a couple

Question 6

Define centre of mass

Answer 6

A point which external forces produce a straight line motion but no rotation

Question 7

Define weight

Answer 7

The gravitational force on an object

Question 8

What is Archimedes principle

Answer 8

Upward force is equal to the weight of the fluid it displaces

Question 9

Define terminal velocity

Answer 9

The constant speed reached when drag force is equal

Question 10

Define moment

Answer 10

The turning effect of a force

Question 11

Define centre of gravity

Answer 11

A point where weight if an object appears to act

Question 12

How do you find the centre of gravity

Answer 12

• Make holes along the edges of the object and let it hang freely from a pin
• It will come to rest with its centre of gravity below the pin
• Hang a plumb line from the pin and draw a line along the plumb line
• Repeat this for the other holes
• Where the lines intersect is the centre of gravity

Question 13

Define drag

Answer 13

It is the frictional force that opposes the motion of the object

Question 14

What does drag depend on

Answer 14

• Density of fluid
• Shape
• Speed

The two most important factors are speed and cross sectional area

Question 15

Determining terminal velocity in fluids

Answer 15

• Put elastic bands around the tube of viscous liquid in fixed distances
• Drop a ball bearing and record the time at which it reaches each band
• Repeat this a few times to reduce random errors
• Calculate time take by the ball to travel between each band and find the velocity

Question 16

What are the principle in moments

Answer 16

When a body is in equilibrium the net force acting on it is zero and it’s net movement is 0.

The sum of clockwise moments = anti-clockwise moments

Moment= force x distance

Question 17

What is a couple

Answer 17

A pair of equal but opposite forces to the object

Question 18

Equation for density

Answer 18

ρ= m/v (kgm⁻³)

Question 19

Equation for pressure

Answer 19

P=F/a (Nm⁻²)

Question 20

Equation for pressure in liquids

Answer 20

P=hρg

ρ=density of the liquid

Question 21

Equation for upthrust

Answer 21

Upthrust= axρg

Question 22

Equation for work done

Answer 22

W=Fx

Question 23

What are the different types of energy

Answer 23

Kinetic 
Gravitational 
Chemical 
elastic potential 
Nuclear
Radiant 
Sound 
Electrical potential 
Thermal

Question 24

What is kinetic energy

Answer 24

Is energy due to the motion of an object with mass

Question 25

What is gravitational potential energy

Answer 25

Energy due to its position in a gravitational field

Question 26

What is chemical energy

Answer 26

Energy contained within bonds between atoms

Question 27

What is elastic potential energy

Answer 27

Is energy stored in a object as a result of reversible change in its shape

Question 28

What is electrical potential energy

Answer 28

Is energy of electrical charges due to their position in an electric field

Question 29

What is nuclear energy

Answer 29

Is energy within the nuclei of an atom

Question 30

What is radiant energy

Answer 30

Is energy oscillated with all electromagnetic waves, stored within the oscillating electric and magnetic fields

Question 31

What is sound energy

Answer 31

Is energy of mechanical waves due to the movement of atoms

Question 32

What is thermal energy

Answer 32

Is the sum of random potential and kinetic energies of atoms in a system

Question 33

Equation for kinetic energy

Answer 33

Ek=0.5mv² W=Fd F=ma W=mad v²=u²+2as W=m x v²/2s x d s and d cancel

Question 34

What is the equation for GPE

Answer 34

Ep=mgh W=Fd F=weight W=mgh

Question 35

Equations for power

Answer 35

P=w/t P=fv v=velocity P=w/t = fx/t (x/t)=velocity

Question 36

Define displacement

Answer 36

Distance traveled in a particular direction

Question 37

Define instantaneous speed

Answer 37

The speed at the moment it's measured

Question 38

Define average speed

Answer 38

The rate of change in distance calculated over a complete journey

Question 39

Define Accelerated

Answer 39

The rate of change of velocity, a vector quantity

Question 40

Define velocity

Answer 40

A vector quantity equal to the rate of change in displacement

Question 41

What is thinking distance

Answer 41

The distance travelled between the moment when you first see a reason to stop

Question 42

What is Breaking distance

Answer 42

Is distance traveled from the moment breaks where applied

Question 43

Define moment

Answer 43

Force X perpendicular distance form the pivot to the line of action of the force