Apulley system has an efficiency of 74.2%. if you perform 200 j of work how much useful work does the pulley perform

148.4 J

Explanation:

We are given that the efficiency of a pulley system is 74.2% and we are to calculate the useful work done if we perform 200 J of work

We know that efficiency is basically the measure of how efficient a process is.

The formula of efficiency is given by:

Efficiency = useful energy output / total energy input

So substituting the given values in the above formula:

0.742 = Useful energy / 200 J

Useful energy = 148.4 J

a and b sometimes have a positive value

the minimum constant speed at which she can catch the train is 2.7 m/s

given:

acceleration = 0.6

time = 4.5 s

to find:

velocity = ?

formula used:

from 1st kinematic equation we get,

v = u + at

u = initial speed of train = 0 m/s

v = final speed of the train

a = acceleration of the train

t = time

solution:

from 1st kinematic equation we get,

v = u + at

u = initial speed of train = 0 m/s

v = final speed of the train

a = acceleration of the train

t = time

v = 0 + (0.6 × 4.5)

v = 2.7 m/s

the minimum constant speed at which she can catch the train is 2.7 m/s