Advertisements
Advertisements
Question
A force acts on a body and displaces it by a distance S in a direction at an angle θ with the direction of the force. What should be the value of θ to get the maximum positive work?
Solution
`W = barF.barS = Fs cos theta`
`cos theta` maximum value 1 = FS
`:. theta = 0^@`
APPEARS IN
RELATED QUESTIONS
The S.I. unit of work is
No work is done by a force if the body
The power of a motor is 40 kW. At what speed can the motor raise a load of 20,000 N?
What happens to the work done when the dispacement of body is at right angles to the direction of force acting on it? Explain your answer.
Name five appliances or machines which use an electric motor.
Its moment of a force scalar or a vector quantity?
A uniform circular motion is an accelerated motion. Justify it.
A man lifts a mass of 10 kg from the floor to a shelf 4 meter high. If g = 10 ms-2, what is the work done?
A weight lifted a load of 200 kgf to a height of 2.5 m in 5 s. calculate: (i) the work done, and (ii) the power developed by him. Take g= 10 N kg-1.
A boy of mass m climbs up a staircase of vertical height h.
- What is the work done by the boy against the force of gravity?
- What would have been the work done if he uses a lift in climbing the same vertical height?
Can work done be zero even if force acts on the body?
Can two agents, doing the same work, have different power?
Name two places in India where electricity is generated from nuclear power plants.
Look at the activity below. Reason out whether or not work is done in the light of your understanding of the term ‘work’.
A donkey is carrying a load on its back.
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.
State whether work is done or not, by writing yes or no, in the following case:
A boy climbs up 20 stairs.