A man of mass of 80kg carries a load of bricks of mass 20kg up a vertical ladder of length 6m.what work has he done?
The work done by the man is equal to the change in potential energy of the load, which can be calculated using the formula:
work = force x distance x cos(theta)
where force is the weight of the load (mg), distance is the height climbed (which is equal to the length of the ladder, 6m), and theta is the angle between the force and the direction of motion (which is 0 degrees since the force is vertical and the motion is also vertical).
So, the work done is:
work = (20kg x 9.8m/s^2) x 6m x cos(0) = 1176 Joules
Therefore, the man has done 1176 Joules of work in carrying the load of bricks up the ladder.
To calculate the work done by the man, we can use the formula:
Work = force × distance
First, we need to find the force applied by the man. This force is equal to the weight of the man and the load combined.
Force = (mass of man + mass of load) × gravitational acceleration
Gravitational acceleration is approximately 9.8 m/s^2.
So, the force applied by the man is:
Force = (80 kg + 20 kg) × 9.8 m/s^2
= 100 kg × 9.8 m/s^2
= 980 N
Next, we need to find the distance over which the force is applied. In this case, it is the height of the ladder, which is 6 m.
Now, we can calculate the work done by the man:
Work = Force × Distance
= 980 N × 6 m
= 5880 J
Therefore, the man has done 5880 Joules (J) of work.