WorksheetsWork and Power
Total questions: 20
Worksheet time: 10mins
Work is done ___________
only when force is applied
on an object
cause the object to move
into the opposite direction
as applied force.
only when force is applied
on an object
cause the object to move
into the same direction
as applied force.
Formula of work:
W = F x t
W = F + t
W = F / d
W = F x d
There are two condition of work to be done....
Constant applied force on the object
Object travel a distance in the same direction of force
Both
The Unit of force is ______________
Kilogram (kg)
Newton(N)
The unit of distance is ___________
meter (m)
centimeter (cm)
millimeter (mm)
Units of work is ___________
Newton (N)
watt (w)
joule (J)
Power is ___________
Is the rate of energy transfer.
Speed of doing work is work done in a certain time.
both
none
Power =
Work + time
Work / time
Work x time
Time is measured in ______________
minutes (min)
hours (hrs)
seconds (s)
Unit of power is:
Meters (m)
Watt (W)
Joules (J)
1. 1 kilowatt (KW) = ____________
2. 1 megawatt (MW) = __________
1. 1000 W
2. 1000000 W
1. 10 W
2. 100 W
1. 100000 W
2. 100 000 000 W
Mechanical Efficiency =
"Output work" / "Input work" x 1%
"Output work" / "Input work" x 10%
"Output work" / "Input work" x 100%
Mechanical efficiency, measure the effectiveness with which a mechanical system performs.
(in short: How strong is my machine)
(in short: How useful is my body)
(in short: How useful is my machine)
Efficiency is always _____________
less than 1%
more than 100%
less than 100
less than 100%
W-out will always be ______________
less than W-in
more than W-in
less than W-out
If a cyclist puts 600 J of work on his bicycle and the bicycle gives out 140 J of useful work. Calculate the efficiency of a cyclist.
{ Work Output / Work Input } × 100 %
= {140 x 600} × 100 %
= 8400000 %
{ Work Output / Work Input } × 100 %
= {140 / 600} × 100 %
= 23.3 %
A heat engine gives out 500 J of heat energy as useful work. Determine the energy supplied to it as input if its efficiency is 40%.
1250 J
456 890 J
A cow weighing 80 kg. sits 6 m. from the fulcrum of a seesaw and just balances the cat on the other side who is seated 10 m. from the fulcrum. How many kilograms does the son weigh?
12 kg
24 kg
48 kg
Efficiency is always less than 100%, why?
Because of cold
Because of heat
Because of friction
Because of the burning effect
How can we increase efficiency?
Reduce the cold
Get more the friction
Drive slower
Reduce the friction
