Advertisements
Advertisements
प्रश्न
A boy weighing 40 kgf climbs up a stair of 30 steps each 20 cm high in 4 minutes and a girl weighing 30 kgf does the same in 3 minutes. Compare:
- The work done by them.
- The power developed by them.
Advertisements
उत्तर
(i) Weight of boy = Force = 40 kgf
Distance travelled in climbing 30 steps each
20 cm high = 30 × 20 = 600 cm = 6 m
Work done in 4 min = W = F × S
= 40 × 6 = 240
Weight of girl = Force = 30 kgf
Distance covered in 3 min = 6 m
∴ Work done in 3 min. = F × S
= 30 × 6
= 180 N
∴ Ratio of work done = 240 : 180 = 4 : 3
(ii) Power = `"W"/"T"`
Power developed by
Boy : Girl
⇒ `240/4 : 180/3`
⇒ 60 : 60
⇒ 1 : 1
संबंधित प्रश्न
kWh is the unit of ______.
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?
The moment of a force 10 N about a point 0 is 4 Nm. Calculate the distance of point of application of force from the point 0.
A mechanic can open a nut by applying a force of 200 N while using a lever handle of 50 cm length. How long handle is required if he wants to open it by applying a force of only 50 N?
What do you mean by uniform circular motion?
How much force is applied on a body when 150 J of work is done in displacing the body through a distance of 10 m in the direction of the force?
In the following case write yes, if the work is being done and no if no work is being done.
A man trying to push a wall.
Justify the statement. “Power can be expressed as the product of force and velocity.”
For the following scenario, state whether the work done by gravity is positive, negative, or zero.
A car in neutral gear is coming down the slope.
