Work, power and efficiency calculations

Question 1

The 2 formulae for WORK

and definition

Answer 1

Work = Force X distance moved Joules (WORK FOR DOUGH)

Work = Power X Time taken Joules

if a body moves because a force acts on it work is being done. If the force is used to keep it still then no work is being done.

Question 2

definition of power

Answer 2

Power is the rate at which work is done

Question 3

2 Formula for power

Answer 3

Power = F X d
——–
s

( NB F x d =Work)

therefore Power =Work
———
s
Watt

Question 4

Formula for efficiency

Answer 4

efficiency = ( useful energy transferred ÷ energy supplied ) × 100

or

input

Question 5

Define mass and explain it

Answer 5

The mass of an object is the amount of matter or “stuff” it contains. The more matter an object contains, the greater its mass. An elephant contains more matter than a mouse, so it has a greater mass. Mass is measured in kilograms, kg, or grams, g.

Question 6

Explain weight

Answer 6

Weight is a force, so it’s measured in newtons. On the surface of the Earth an object with a mass of 1 kg has a weight of about 10 N.

The mass of an object stays the same wherever it is, but its weight can change. This happens if the object goes somewhere where gravity is stronger, or weaker, such as the Moon.

The Moon has less mass than the Earth, so its gravity is less than the Earth’s gravity. This means that objects weigh less on the Moon than they do on the Earth.Although the mass stays the same on either planet

Question 7

define momentum and state the formula with units

Answer 7

Momentum is a property of moving objects. We can calculate momentum using

momentum = mass x velocity
P = M X V     kg m/s

Question 8

define weight and give formula

Answer 8

Weight is the the FORCE on the object due to gravity
Weight = Mass × Gravity
W = mg
Its a SI Unit
Because its a force then its measured in Newtons

Question 9

What is Kinetic energy and the formula

Answer 9

The energy that a body possesses by
virtue of the fact that it is moving is called kinetic
energy. The kinetic energy that a body possesses is
equal to the amount of work that must have been
done to it to increase its velocity from zero to
whatever velocity it has. For a mass m moving
with velocity v:

Kinetic energy = 1 mv²

Question 10

What is Kinetic energy and the formula

Answer 10

The energy that a body possesses by
virtue of the fact that it is moving is called kinetic
energy. The kinetic energy that a body possesses is
equal to the amount of work that must have been
done to it to increase its velocity from zero to
whatever velocity it has. For a mass m moving
with velocity v:

Kinetic energy KE = 1/2 mv² kg/m²/s²

mass
velocity