Question

One workman is measured as having a power of 528W. His weight is 800N. He can develop the same power climbing a ladder, whose rungs are 30cm apart. How many rungs can he climb in 5 seconds?​

Answer 1

Power = Work / tiime = force * distance / time = mass * gravity * height / time

so 528 = 800 * h / 5

h= 528 * 5 / 800 = 3.3 m

and this is 11 rungs on the ladder.

Hope it's Helpful for you...☺☺

Answer 2

Let's suppose, the worker climbs 'n' rungs of ladder. Thus, the potential energy gained by him is:  

E = vertical displacement X gravity X mass ( E = mgh )  

Now, his weight ( = mg ) = 800N.  

So, E = 800 X .3n = 24000n  

Now, the time taken by time is 5 seconds. Thus power needed to climb 'n' rungs in 5 seconds is:  

P = Energy/Time  

= 240n/5  

= 48n  

Now, 528W >= 48n (Man must posses more or equal power than what is required)  

Therefore, n <= 528/48  

Hence, n = 11  

The man can climb 11 rungs n 5 seconds.