Topic 1 - Waves, Light

Question 1

What is the equation for weight?

Answer 1

W = mg

Weight = mass x gravity

Question 2

What’s the difference between a scalar and vector quantity?

Answer 2

Scalar = A quantity that takes into account magnitude and unit but not direction.
Vector = A quantity that takes into account magnitude, unit and direction.

Question 3

What are the equations for speed?

Answer 3

S = d/t
S = (u+v)/2

Question 4

What is the equation for acceleration?

Answer 4

A = (v-u)/t

Question 5

What’s the equation for force?

Answer 5

F = ma

Force = mass x acceleration

Question 6

What’s the equation for density?

Answer 6

D = m/v

Density = mass / volume

Question 7

What’s the equation for hooke’s law?

Answer 7

F = ke

Force = spring constant x extension

Question 8

What’s the equation for pressure?

Answer 8

P = f/a

Pressure = force / area

Question 9

What are the equations for a moment?

Answer 9

M= fd

Moment = force x distance from pivot

F1 x D1 = F2 x D2

Question 10

A car travels 125m in 6.6 seconds. What was the cars speed?

Answer 10

WIK: d=125m, t=6.6s, s=?
S=d/t
S= 125/6.6 = 18.93m/s

Question 11

A car starts at rest and increases its velocity to 10m/s in 3 seconds. What was the cars acceleration?

Answer 11

WIK: t=3s, u=0m/s, v=10m/s,a=?
A=(v-u)/t
A=(10-0)/t = 10/3 = 3.33m/s2

Question 12

What is friction?

Answer 12

Friction is a force that opposes motion

Question 13

How do you work out the resultant force?

Answer 13

Fr = f1 +f2

Question 14

Work out the resultant force of this object.

20N 100N

Answer 14

WIK: F1=-20N, F2=100N, Fr=?
Fr = F1 + F2
Fr = -20 + 100 = 80N

Question 15

What is the formula for efficiency?

Answer 15

E = UE/TE

Efficiency = Useful Energy / Total Energy

Question 16

List the 5 forms of energy?

Answer 16

• Chemical
• heat
• electrical
• sound
• light
• magnetic
• strain
• kinetic
• gravitational potential

Question 17

What is chemical energy?

Answer 17

Energy that’s stored eg - batteries, fossil fuels etc…

Question 18

What is heat energy?

Answer 18

Energy that increases the temperature

Question 19

List examples of objects that produce sound energy

Answer 19

speakers, radio, engine etc…

Question 20

What is light energy?

Answer 20

Energy that lets us see things

Question 21

What is magnetic energy?

Answer 21

Energy which creates attractive or repulsive forces when in contact with metal

Question 22

What is strain energy?

Answer 22

Stored energy within a stretched material

Question 23

What is gravitational potential energy?

Answer 23

Stored energy in an object based on its height above a point

Question 24

What is the formula for Gravitational Potential Energy (GPE)?

Answer 24

GPE = mgh

GPE = mass x gravity x height from ground

Question 25

Convert the equation for GPE so that it equals mass.

Answer 25

GPE = mgh M = GPE / gh

Question 26

Convert the equation for GPE so that it equals the height of an object from the ground.

Answer 26

GPE = mgh h = GPE / mg

Question 27

A football is kicked 10m into the air, where it has a GPE Of 40J. What is the mass of the ball?

Answer 27

WIK : GPE = 40J, h = 10m, g = 10N/kg, m = ? ``` GPE = mgh m = GPE / gh m = 40/10x10 = 40/100 = 0.4kg ```

Question 28

What is the equation for work?

Answer 28

Work Done = Force x Distance moved in direction of force WD = Fxd

Question 29

What is the equation for kinetic energy?

Answer 29

Kinetic energy = 1/2 x mass x velocity squared K = 1/2 x mv2

Question 30

Find the speed of a boat if it’s mass is 1200kg and it has a kinetic energy of 9600J.

Answer 30

WIK: KE = 9600J, m = 1200kg, v = ? ``` KE = 1/2 x mv2 2KE = mv2 2KE/m = v2 V2 = 2x9600/1200 = 19200/1200 = 16 V = square root of 16 = 4m/s ```

Question 31

What is the equation for power?

Answer 31

P = wd/t Power = Work done / time

Question 32

What is Hookes law?

Answer 32

the strain in a solid is proportional to the applied stress within the elastic limit of that solid