P1 - 1.3 Kinetic Energy

Question 1

What is kinetic energy

Answer 1

Energy that an object possesses due to its motion

Question 2

True or False:
A plane has kinetic energy

Answer 2

True

Question 3

True or False:
A particle has kinetic energy

Answer 3

True

Question 4

True or False:
A standstill object has kinetic energy

Answer 4

False

Question 5

True or False:
A moving object has kinetic energy

Answer 5

True

Question 6

What 2 things depend on how much energy an object has

Answer 6

Speed
Mass

Question 7

If we have a mast moving object how does it affect the kinetic energy

Answer 7

It will have more kinetic energy

Question 8

How does mass affect how much kinetic energy do we have

Answer 8

More mass will mean there is more kinetic energy (as long as speed is the same)

Question 9

Both objects are moving at 900m/s What has more kinetic energy:
- a plane weighing 20 tonnes
- a particle weighing 0.1g

Answer 9

A plane weighing 20 tonnes will have more kinetic energy

Question 10

What equation do we use to calculate kinetic energy

Answer 10

Kinetic energy = 1/2 x mass x velocity^2

Question 11

What is this symbol for: v

Answer 11

Velocity

Question 12

What does this symbol stand for: m

Answer 12

Mass

Question 13

What does this symbol stand for: Ek

Answer 13

Kinetic energy

Question 14

What is mass measured in in kinetic energy calculations

Answer 14

Kilograms

Question 15

What is kinetic energy measured in

Answer 15

Joules

Question 16

What is velocity measured in in kinetic energy

Answer 16

Metres per second
m/s

Question 17

What should you do before starting an equation

Answer 17

Check everything is in the same measurements (etc changing grams to to kilograms)

Question 18

How many tonnes are in a kilogram

Answer 18

1000

Question 19

Which has more kinetic energy:
Particle with a speed of 4000m/s and weight of 0.1g or a plane with a speed of 5m/s and a weight of 20 tonnes

Answer 19

Ek = 1/2x(m)x(v^2)

1) convert all the measurements
Particle: 0.1g —> kg
0.1/1000 =0.0001
Plane: 20tonnes —> kg
20x1000=20,000

2) put values into equation
Plane: (0.5 x 20,000)x5^2=250,000J
Particle: (0.5 x 0.0001)x4000^2=800J

3) double check you have answered the question: it is asking which has more kinetic energy

= the plane has more kinetic energy

Question 20

An object has a mass of 2 kg, and is travelling at a velocity of 5 m/s.

How much kinetic energy does the object have?

Answer 20

Ek=1/2x(m)x(v^2)
Ek= (0.5x2)x5^2=25
Ek= 25J

Question 21

A cyclist is riding down a hill at a speed of 10 m/s.

The cyclist has 4 kJ of kinetic energy.

Calculate the cyclist’s mass.

Answer 21

Ek=1/2x(m)x(v^2)
1) rearrange the question
m= Ek/0.5xv^2
2) convert the units
4kJ —> J = 4x1000=4,000J
4000/0.5x(10^2)=80kg

Question 22

How would you rearrange the kinetic energy calculation to find mass

Answer 22

Mass= kinetic energy/ 0.5 x velocity^2

Question 23

How would you rearrange the kinetic energy calculation to find velocity

Answer 23

Velocity = square root( kinetic energy/ 0.5 x mass)