A machine has a velocity ratio of 6 and is 80% efficient. What effort would be needed to lift a load of 300N with the aid of this machine.
The effort needed to lift a load of 300N with the aid of this machine would be 50N. This can be calculated by multiplying the load (300N) by the velocity ratio (6) and then multiplying the result by the efficiency (0.8). 300 x 6 x 0.8 = 50N.
I am going to scream!
The 80 % efficiency means you need MORE effort, not less
0.8 * effort force = 300/6
so
300 / (0.8 * 6)