physics revisoin

what are scalar quantities

a quantity that only has size

what are vector quantities

a quantity with size and direction

what is displacement

how far an object has moved from its original position

or

the distance between two points

what is speed

the distance covered per unit time

equation for speed

speed = distance / time

what is the equation for velocity

velocity = displacement / time

a runner runs 400 metres west then 800m south. then they run west again for 1200m before finishing with 800m north . the whole run took 800 seconds.

what is the displacement of the runner?

what is the average speed of the runner?

what is a resultant vector

is the combination of 2 or more single vectors

what is newtons 3rd law

every action has an equal and opposite reaction

if the tyres exert a force on the road what does the road do

exert an equal and opposite reaction on the tyres

what is newtons 1st law

an objects motion will not change unless acted upon by an unbalanced force

what is acceleration

the rate of change in velocity

what does a negative acceleration mean

the object is decelerating

if an object is moving in a circle is it accelerating or deceleration

it’s accelerating as the object is constantly moving

what is the equation of acceleration

calculate the acceleration of a car that goes from rest to 10 m/s forward in 5 seconds

acceleration = change in velocity / time

a = 10 m/s - 0 m/s /5 s

a = 2m/s²

what is internal energy

it is the total kinetic and potential energy of all the particles in a system

what are thermal transfers

the movement of heat energy from one place or object to another

what is specific heat capacity

the amount of energy required to raise the temperature of 1 kg of a substance by 1ºC.

how do you calculate the amount of energy stored in or released from a system as its temperature changes (specific heat capacity)

rearrange the equation so we can find mass

A copper kettle has a mass of 0.8 kg. Calculate the thermal energy stored in the kettle when its temperature rises from 25∘C to 100∘C. The specific heat capacity of copper is 385 J/(kg∘C).

Formula Used: ΔE = m × c × Δθ

How to Solve:

1. Identify the knowns:

   • Mass (m) = 0.8 kg

   • Specific Heat Capacity (c) = 385 J/(kg∘C)

   • Initial Temperature = 25∘C

   • Final Temperature = 100∘C

2. Calculate the change in temperature (Δθ):

   • Δθ=Final Temperature−Initial Temperature

   • Δθ = 100∘C − 25∘C = 75∘C

3. Substitute the values into the formula:

   • ΔE = 0.8 kg × 385 J/(kg∘C) × 75∘C

4. Calculate the result:

   • ΔE = 23100 J

Answer: The thermal energy stored in the kettle is 23100 J.

A 3 kg block of lead cools down, releasing 27600 J of thermal energy. If the temperature of the lead changed by 20∘C, what is the specific heat capacity of lead?

Formula Used: Rearranged from ΔE = m × c × Δθ to c = ΔE / (m × Δθ)

How to Solve:

1. Identify the knowns:

   • Change in Thermal Energy (ΔE) = 27600 J

   • Mass (m) = 3 kg

   • Change in Temperature (Δθ) = 20∘C

2. Substitute the values into the rearranged formula:

   • c = 27600 J / (3 kg × 20∘C)

3. Calculate the denominator first:

   • 3 kg × 20∘C = 60 kg∘C

4. Perform the division:

   • c = 27600 J / 60 kg∘C

   • c = 460 J/(kg∘C)

Answer: The specific heat capacity of lead is 460 J/(kg∘C).

what is specific latent heat

the amount of energy required to change the stat of 1 kg of a substance by no change in temp.

how do you calculate the energy change taking place when an object changes state (specific latent heat)

what are the 2 types of waves

longitudinal and transverse

do waves transfer energy using matter

no they are transferred by oscillations

do the objects producing the wave in longitudinal waves vibrate parallel or perpendicular to the direction of the waves energy transfer

parallel

do the objects producing the wave in transverse waves vibrate parallel or perpendicular to the direction of the waves energy transfer

perpendicular at 90∘

what is an example of transverse waves

light and water waves

what is an example of a longitudinal wave

sound waves

what do both waves transfer

energy

what is the peak in a wave

the maximum point of a wave

what is the trough in a wave

the minimum point of a wave

what is the wavelength

the distance from one point of a wave to the same spot on the next wave

what is the amplitude

the maximum distance of a point on the wave from its rest position

what is frequency

the number of waves that pass by each second. Unit = Hz, hertz

what is a period

the amount of time it takes a wave to pass a given point. Unit = s, seconds

what is the equation for frequency

what is the equation for period?

period = 1 / frequency

how do you work out the velocity of a wave

what does luminous mean and non luminous mean

luminous - gives out light

non luminous - does not give out light

what does opaque and translucent mean

opaque - light cannot be transmitted

translucent - some light can be transmitted but it is not very clear

what is refraction

refraction is when light (or other waves) changes direction as it passes from one transparent medium into another, due to a change in its speed.