Advertisements
Advertisements
प्रश्न
Determine the amount of work done when an object is displaced at an angle of 30° with respect to the direction of the applied force.
Advertisements
उत्तर
Suppose, when a constant force `vecF` is applied on a body located at point 'O', the displacement of that body is `vecs` and the angle between force and displacement is θ.
Displacement of body O →P, direction of force O →Q
On the basis of the diagram,
`costheta = ("OR")/("OQ")`
∴ OR = OQ cosθ
= F cosθ
Here the force applied on the body in the direction of displacement
= F cosθ
∴ Work done by force = (F cosθ)s = Fs cosθ
Displacement of body O →P, direction of force O →Q
`cos theta = ("OS")/("OP")`
∴ OS = OP cosθ = s cosθ
Here the displacement of the body in the direction of the force = s cosθ
∴ work done by force on body = F(s cosθ) = Fs cosθ
When θ = 30°, work (W) = Fs cos 30°
= Fs`sqrt3/2`
APPEARS IN
संबंधित प्रश्न
A body, when acted upon by a force of 10 kgf, moves to a distance 0.5 m in the direction of force. Find the work done by the force. Take 1 kgf = 10 N.
When is work said to be done by a force?
The power of a motor is 40 kW. At what speed can the motor raise a load of 20,000 N?
A boy weighing 25 kgf climbs up from the first floor at height 3 m above the ground to the third floor at height 9m above the ground. What will be the increase in his gravitational potential energy? (Take g = 10 N kg -1)
How much work is done by the gravitational force of earth acting on a satellite moving around it in a circular path? Give reason for your answer.
A girl is carrying a school bag of 3 kg mass on her back and moves 200 m on a levelled road. If the value of g be 10 m/s2, the work done by the girl against the gravitational force will be :
The work done on an object does not depend on the :
Why is the work done on an object moving with uniform circular motion zero?
A man carrying a suitcase in his hand is walking horizontally. What is the work done against gravity?
Write an expression for work done by a force depends?
Complete the following sentences:
Joule is the unit of .......
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 girl of mass 50 kg runs up a flight of 40 steps in 20 seconds. If each step in 20 cm high, calculate the power developed by the girl. (g= 10 ms-2).
Give an example
Electrical energy changes to heat energy.
Can two agents, doing the same work, have different power?
What should be the characteristic of a source of energy?
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?
State whether work is done or not, by writing yes or no, in the following case:
A man pushes a wall.
