P1

Question 1

What are the different energy stores ?

Answer 1

Chemical energy storer (fuels,food). Kinetic energy (moving). Gravitional poterntial energy (eg an object above the ground). Elastic potential( energy stored in a spring . Thermal (temprature)

Question 2

Describe the energy transfer of a brick falling from a building ?

Answer 2

It energy starts in gravitional poterntial energy deacring and turning into kinetic enegy. Contact then makes it go into the thermal energy store via sound waves and forces heating up

Question 3

What energy transfer happens to a bungee jump after jumping of the platform?

Answer 3

When the rope is straight the gravitational potential energy stores to the kinetic energy stores as the jumper accelerates towards the ground due to gravity. When it tightens the kinetic eneergy deacreses and the ropes eleastic energy increases

Question 4

What is the formula to find work done ?

Answer 4

Work done (joules ) = force applied (newtons) x distance moved along the line of action if the force (meters)

Question 5

A builder pushed a wheelbarrow for 5 meters across flat grounds with a force of 50N . What is the work done?

Answer 5

Work done = force applied x distance moved
= 50 N x 5.0m
= 250J

Question 6

What energy is made to overcome friction ?

Answer 6

Thermal energy

Question 7

What is the formula for change in objects gravitational potential energy store ?

Answer 7

Change objects gravitational potential energy (j) = weight (n) x change of height (meters)

Question 8

A student of weight 300N climbs om a platform that is 1.2 meters higher than the floor. Calculate the gravitational potential energy store

Answer 8

Increase of Ep = 300N x 1.2m = 360J

Question 9

What is the formula for change of gravitational potential energy store ?

Answer 9

Change in gravitational potential energy store (j) = mass (kilograms) x gravitational field strength (newtons per kilogram) x change of height ( meters)

Question 10

What is the kinetic energy equation?

Answer 10

Kinetic energy = 1/2 x mass (kilogram ) x speed squared (meters per second )

Question 11

Calculate the kinetic energy soted in a vechile of the mass 500kg moving at 12m/s

Answer 11

Kinetic energy = 1/2 m v squared
=0.5 x 500kg x (12x12) m/s
= 36000J

Question 12

What is the formula for elastic potential energy ?

Answer 12

Elastic potential enerrgy = 1/2 x spring constant(newtons per metere) x extension squared (meters)

Question 13

What is useful energy ?

Answer 13

Is energy transferred to where it is wanted in the way that is wanted

Question 14

What is wasted energy ?

Answer 14

Is energy that is not usefully transferred

Question 15

What is the wasted energy in a kettle ?

Answer 15

Thermal energy from the hear coming out the kettle

Question 16

What is the formula for efficiency ?

Answer 16

Efficency = useful output energy transffered by the device (joules) /
total input energy supplied to the device (joules) x 100

Question 17

What is the formula for power ?

Answer 17

Power (watts) = energy transferred to appliance (joules )/ time taken for energy to be transferred (seconds )

Question 18

What is the useful energy light bulb ?

Answer 18

Light emitted from the glowing filament

Question 19

What is the wasted energy In a light bulb?

Answer 19

Energy transfer from the filament hearing the surroundings

Question 20

How do you find wasted power ?

Answer 20

Power wasted = total power in - useful power out