Advertisements
Advertisements
प्रश्न
A boy of weight 40 kgf climbs up the 15 steps, each 15 cm high in 10 s and a girl of weight 20 kgf does the same in 5 s. Compare:
- the work done, and
- the power developed by them. Take g = 10 N kg-1.
Advertisements
उत्तर
Weight of boy = 40 kgf
No. of steps = 15; Each = 15 cm; Time = 10 sec
Force of gravity on boy -
F1 = m1g = 40 × 10 = 400 N
Force of gravity on girl -
F2 = m2g = 20 × 10 = 200 N
Total height climbed (h) = 15 × 15 = 225 cm = 2.25 m
(i) Work done by boy -
W1 = F1 × h = 400 × 2.25 = 900 J
Work done by Girl -
W2 = F2 × h = 200 × 2.25 = 450 J
W1 : W2 = `900/450 = 2/1`
W1 : W2 = 2 : 1
(ii) Power = `"work done"/"Time taken"`
t1 = 10 sec; t2 = 5 sec
P1 [Boy] = `(900 " J")/(10 " s")` = 90 W
P2 [Girl] = `(450 " J")/(5 " s")` = 90 W
P1 : P2 = 90 : 90 = 1 : 1
संबंधित प्रश्न
Fill in the blank with suitable word :
Work is measured as a product of __________ and __________
A boy throws a rubber ball vertically upwards. What type of work, positive or negative, is done : by the force applied by the boy?
(a) by the force applied by the boy?
(b) by the gravitational force of earth?
Why does a spanner have a long handle?
Fill in the boxe to show the corresponding energy transformation.
How is horse power related to the S. I. unit of power?
Define Translational motion.
Who is the odd one out?
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?
