Advertisements
Advertisements
Question
Advertisements
Solution
SI unit of power = watt
CGS unit of power = erg per second
1` W = 1 J s -1 = 107 erg s -1
APPEARS IN
RELATED QUESTIONS
When does a force perform work?
Give reasons for the following A teacher moving around in the class is doing work but a child standing and reading a book is not doing any work.
A boy of mass 40 kg climbs up the stairs and reaches the roof at a height 8 m in 5 s. Calculate:
- the force of gravity acting on the boy,
- the work done by him against the force of gravity,
- the power spent by boy. (Take g = 10 m s-2)
A machine raises a load of 750 N through a height of 16 m in 5 s. calculate:
- energy spent by machine,
- power at which the machine works.
How many watts equal one horse power?
Write an expression for the work done against gravity.
Give an example
Electrical energy changes of sound energy.
A block of mass 30 kg is pulled up a slope, as shown in diagram with a constant speed, by applying a force of 200 N parallel to slope.
A and B are initial and final positions of block.

(i) Calculate the work done by force in moving the block from A to B.
(ii) Calculate P.E. gained by block. [g=10ms-2]
