Advertisements
Advertisements
Question
Look at the activity below. Reason out whether or not work is done in the light of your understanding of the term ‘work’.
A sailboat is moving due to wind energy.
Advertisements
Solution
- Wind energy applies a force on the sailboat to push it in the forward direction.
- Therefore, there is a displacement in the boat in the direction of force.
- Hence, work is done by wind on the boat.
APPEARS IN
RELATED QUESTIONS
The S.I. unit of energy is .............
State two advantage of producing hydroelectricity.
How much work is done when a force of 2 N moves a body through a distance of 10 cm in the direction of force?
Nm is the unit of .......
A cricket ball is thrown up from the earth's surface. What happens to its P.E.
(a) during the motion
(b) at the highest point?
An electric motor drives a machine which lifts a mass of 4 kg through a height of 10 m in 5 s at a constant speed. Assuming g = 10 ms-2, calculate
(i) the amount of work done, (ii) the power of the machine.
Fill in the boxe to show the corresponding energy transformation.

Give an example
Electrical energy changes of sound energy.
Give an example
Electrical energy changes to heat energy.
An electric motor of power 100 W is used to drive the stirrer in a water bath. If 50% of the energy supplied to the motor is spent in stirring the water. Calculate the work done on the water in one minute.
