Advertisements
Advertisements
Question
In which of the following cases is work being done:
- A boy pushing a heavy rock
- A boy climbing up the stairs
- A coolie standing with a box on his head
- A girl moving on the road.
Solution
work being done in the following cases
(b) A boy climbing up the stairs
(d) A girl moving on the road.
APPEARS IN
RELATED QUESTIONS
Write an expression for the work done when a force is acting on an object in the direction of its displacement.
Name a common device where a gear train is used
Define the term energy.
How is work related to energy?
The power of a motor is 40 kW. At what speed can the motor raise a load of 20,000 N?
What is the SI unit of work?
A 100 W electric lamp emits energy in the form of light at the rate 10 J per second. What percentage of electric energy does the lamp transform into light 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]
(i) A 200g ball is thrown vertically upward with an initial velocity of 30 ms-1. Draw a velocity-time graph for the motion of ball.
(ii) How long will the ball take to reach the highest point?
(iii) What will be the kinetic energy of ball, when it returns to the starting point, neglecting the air resistance?
(iv) What will be the potential energy of ball at highest point?
If a ball is dropped on the sloping roof of a house, it acquires ______ and falls on the ground. That is the transformation of ______ energy into ______ energy takes place.
(kinetic, potential, motion)
Look at the activity below. Reason out whether or not work is done in the light of your understanding of the term ‘work’.
A wind-mill is lifting water from a well.
Look at the activity below. Reason out whether or not work is done in the light of your understanding of the term ‘work’.
An engine is pulling a train.
Force acting on a particle moving in a straight line varies with the velocity of the particle v as F = `K/v`, where K is a constant. The work done by this force in time t is
A body of mass 0.5 kg travels on straight line path with velocity v = (3x2 + 4) m/s. The net work done by the force during its displacement from x = 0 tox = 2 m is ______.
A uniform chain of length 2 m is kept on a table such that a length of 60 cm hangs freely from the edge of the table. The total mass of the chain is 4 kg. What is the work done in pulling the entire chain on the table?
