Advertisements
Advertisements
प्रश्न
A coolie carrying a load on his head and moving on a frictionless horizontal platform does no work. Explain the reason why.
Advertisements
उत्तर
We know W = F d cos θ.
Since force is normal to displacement.
So θ = 90°
Hence work done W = Fd cos θ 90 = 0.
संबंधित प्रश्न
If the power of a motor is 100 kW, at what speed can it raise a load of 50,000 N?
When does a force do work?
When a body moves in a circular path, how much work is done by the body? Give reason.
(Hint: The body is acted upon by the centripetal force.)
A man spends 7.4 KJ energy in displacing a body by 74 m in the direction in which he applies force in 2.5 s. Calculate the force applied.
A body of mass m is moving with a uniform velocity u. A force is applied on the body due to which its velocity changes from u to v. How much work is being done by the force?
Justify the statement. “Power can be expressed as the product of force and velocity.”
A machine raises a load of 750 N through a height of 16 m in 5 seconds. Calculate the power at which the machine works.
A man weighing 700 N runs up a flight of 15 steps, each 20 cm high, in 5 seconds. Calculate the power of the man.
A force of 1 kgf displaces a body by a distance of 10 cm
(i) in direction of force,
(ii) normal to the force
(iii) at an angle of 60° to the direction of the force.
Calculate the amount of work done in each case. (Take: g = 9.8 ms−2 )
