A crane lifts a 200kg load at a steady velocity.It takes 12s to raise the load through 60m.

i) What is the power needed to lift the load if there is no friction?

ii) What is the power needed if the friction force is constant at 170N?

power=work/time=200(9.8)60/12 watts

if friction
power= (170*60) +power above

To answer these questions, we need to understand the concept of power and how it is calculated.

Power (P) is defined as the rate at which work is done, or the rate at which energy is transferred or transformed. Mathematically, power is calculated using the formula:

P = Work/Time

Where "Work" is the amount of work done, and "Time" is the time it takes to do that work. In this case, the work done is the work done by the crane to lift the load, and the time taken is given in the problem.

Now let's solve the questions step by step:

i) What is the power needed to lift the load if there is no friction?

In this case, since there is no friction, all the power is used to lift the load. The power needed can be calculated using the formula mentioned above.

Power = Work/Time

To find the work done, we can use the formula:

Work = Force x Distance

In this case, the force is equal to the weight of the load, which is given as 200 kg, and the distance is given as 60 m. So, the work done can be calculated as:

Work = 200 kg x 9.8 m/s^2 x 60 m

Now, we have the work done and the time taken, which is given as 12 seconds. By substituting these values into the power formula, we can find the power needed to lift the load:

Power = Work/Time

ii) What is the power needed if the friction force is constant at 170N?

In this case, we need to consider the friction force while calculating the power needed. The friction force opposes the motion and requires additional work from the crane to overcome it.

To find the net force acting on the load, we subtract the friction force from the weight of the load:

Net Force = Weight - Friction Force
= 200 kg x 9.8 m/s^2 - 170 N

Now, we can calculate the work done by the net force:

Work = Net Force x Distance

By substituting the values of the net force and distance into the formula, we can calculate the work done. Once we have the work done and the time taken, we can find the power needed using the power formula mentioned above:

Power = Work/Time