Advertisements
Advertisements
Question
Ravi applied a force of 10 N and moved a book 30 cm in the direction of the force. How much was the work done by Ravi?
Advertisements
Solution
Given:
Force (F) = 10 N,
Displacement (s) = 30 cm
= 30 × 10−2 m
Find: Work done (W) = ?
Formula: W = F × s
Calculations:
W = 10 × 30 × 10−2
W = `(10 xx 30)/100`
W = 3 J
Work done by Ravi is 3 J.
APPEARS IN
RELATED QUESTIONS
When do we say that work is done?
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.
Why is a jack screw provided with a long arm?
A coolie does no work against the force of gravity while carrying a luggage on a road.
State two conditions when no work is done by a force.
Differentiate between energy and power.
A box of weight 150 kgf has gravitational potential energy stored in it equal to 14700 J. Find the height of the box above the ground. (Take g = 9.8 N kg-1)
Find the kinetic energy of a body of mass 1 kg moving with a uniform velocity of 10 m s-1.
Define 1 joule of work.
What are the quantities on which the amount of work done depends? How are they related to work?
The velocity of a car increases from 54 km/hr to 72 km/hr. How much is the work done if the mass of the car is 1500 kg?
A woman pulls a bucket of water of total mass 5 kg from a well which is 10 s. calculate the power used by her.
A block of mass 20 kg is pulled up a slope (fig.12) with a constant speed by applying a force of 500 N parallel to the slope. A and B are initial and final positions of the block.
(a) Calculate the work done by the force in moving the block from A and B.
(b) Calculate the potential energy gained by the block.
Give an example
Electrical energy changes to heat energy.
A coolie, with a load of 30 kg on his head, walks on the platform. If he walks a distance of 60 m, what is the work done by him?
A girl of mass 40 kg runs a height of 80 stairs, each 25 cm high with a load of 20 kg on her head in 25 sec. If g is 10 m/s2, find:
(i) Gravitational force acting on the girl.
(ii) Work done by her.
(iii) Useful work done by her.
(iv) Her power in watt.
