Advertisements
Advertisements
प्रश्न
A boy weighing 350 N climbs up 30 steps, each 20 cm high in 1 minute, Calculate:
- the work done and
- power spent.
Advertisements
उत्तर
Force = weight of body = 350 N
Total distance = h = 30 × 20 = 600 cm
h = `600/100 = 6m`
(i) Work done W = F × h
W = 350 × 6 = 2100 J
(ii) Power spent = `"Work done"/"Time taken" = (30 × "Mg" × "h")/(1 " minute")`
= `((30 × 350 ×20)/100)/(1 " minute")`
= `(2100 J)/(1 " minute")`
= `(2100 J)/(60 " Sec")`
Power spent = 35
APPEARS IN
संबंधित प्रश्न
The work done by a fielder when he takes a catch in a cricket match, is negative. Explain.
Differentiate between work and power.
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.
Work is a scalar quantity because it is a measure of transfer of energy without indicating any direction
A boy takes 3 minutes to lift a 20 litre water bucket from a 20 m deep well, while his father does it in 2 minutes. Compare:
- the work, and
- power developed by them.
A boy takes 3 minutes to lift a 20 litre water bucket from a 20 m deep well, while his father does it in 2 minutes.
How much work each does? Take density of water = 103 kg m-3 and g = 9.8 N kg-1.
State the condition when the work done by the force is negative.
A force F when acts on a body, displace it by a distance d in a direction at an angle θ with the direction of the force. Write down the expression for the work done by the force.
The world record for weight lifting was held by Sergei Didyk of the USSR. He lifted 261 kg to a height of 2.3 m in 4s; find:
(a) Weight lifted by him
(b) Work done by him
(c) Power developed by him. (g = 10m/s2)
A coolie carries a load of 30 kgf through a distance of 500 m in 5 minutes while another coolie B carries the same load through the same distance in 10 minutes. Compare the
(i) work done, and
(ii) power developed. (Take: g = 10md−2)
