Energy

Question 1

What is a force?

Answer 1

A push or pull or twist in a particular direction.

Question 2

Name a few forces.

Answer 2

Thrust, lift, air resistance, normal contact, tension, elastic, friction, Gravity or weight, upthrust.

Question 3

What are 4 forces on free body diagram of car?

Answer 3

Normal contact
Friction car Thrust
Gravity(weight)

Question 4

What is difference between scalar and vector quantities?

Answer 4

Scalar quantities have size only no direction
(Mass)
Vector quantities have both size and direction
(Velocity)

Question 5

What is resultant force?

Answer 5

More than one force acting on an object can be replaced by a single overall force.

Question 6

What is mass and what is weight?

Answer 6

Mass is amount of matter. (kg)
Weight is force of gravity on an object. (N)

Question 7

What equation is used to calculate weight?

Answer 7

Weight = mass*gravitational field strength

Question 8

What is it called when objects change shape due to force exerted on them?

Answer 8

Deformation

Question 9

What happens to elastic material when force is removed?

Answer 9

Regains its og shape.

Question 10

How to calculate Force?

Answer 10

Force = spring constant*extension
(N) (N/m) (m)

F = k e

Question 11

How to calculate efficiency?

Answer 11

efficiency=useful energy/total energy

Question 12

What is kinetic energy?

Answer 12

Energy in moving objects.

Question 13

How to calculate kinetic energy?

Answer 13

Ek = 1/2 x mass x speed²

Question 13

How to calculate work done?

Answer 13

Work done= Force*displacement

Question 14

How to calculate GPE?

Answer 14

Ep = mass x gravity field strength x height

Question 15

How to calculate energy transferred (thermal) ?

Answer 15

energy transferred=mass x specific heat capacity x temp change

Question 16

How to calculate power?

Answer 16

Power=energy transferred/time taken

Question 17

How to calculate Ee?

Answer 17

elastic potential energy = 0.5 × spring constant × (extension) ²

Question 18

What is a scalar quantity?

Answer 18

Where just the magnitude is given.

Question 19

What is vector quantity?

Answer 19

Where magnitude + direction is given.

Question 20

What is distance?
(Scalar or vector)

Answer 20

Distance - Total length of the journey . It has a magnitude but no direction . Therefore distance is a scalar.

Question 21

Equation for speed:

Answer 21

Speed = Distance / time

Question 22

Equation for velocity:

Answer 22

Velocity = Displacement / Time

Question 23

How to determine if something is scalar or vector using equation?

Answer 23

If one thing is vector in equation answer is vector. If both scalar it is scalar.

Question 24

Examples of scalar :

Answer 24

Area,mass, speed, distance, time, energy transferred and power

Question 25

Examples of vector :

Answer 25

Velocity, friction, displacement, upthrust, weight, momentum

Question 26

Definition of contact force:

Answer 26

A contact force is any force that occurs as a result of two objects making contact with each other.

Question 27

Definition of non-contact force:

Answer 27

A non-contact force is a force which acts on an object without coming physically in contact with it.

Question 28

What is ‘limit of proportionality’?

Answer 28

When the spring is to far extended and does not return to its original shape.

Question 29

What happens when we stretch a spring?

Answer 29

1) Force is applied to change the length of it
2) When we put in energy it is stored within it
3) THis energy is called elastic potential energy

Question 30

How do we calculate GRAVITATIONAL POTENTIAL ENERGY?

Answer 30

Ep = m * g * h

(j) (Kg) (N/Kg) (m)
Ep = mass * gravitational field strength * height

Question 31

How do we calculate CHANGE IN THERMAL ENERGY?

Answer 31

△E = m * c * △θ
(J) (Kg) (J/Kg) (°C)

△E = mass * specific heat capacity * temp change

Question 32

Definition of work done :

Answer 32

Whenever energy is transferred from one store to another.

Question 33

The equation for WORK DONE?

Answer 33

Work done = Force * Distance

Question 34

The equation for POWER :

Answer 34

Power = Work done / time

Question 35

Definition of a watt :

Answer 35

1 watt is an energy transfer of 1 J per second

Question 36

The equation for EFFICIENCY :

Answer 36

Efficiency = Useful / Total energy

Question 37

2 Ways to increase efficiency :

Answer 37

Insulation
Lubriication