Show that 480 W of power is expended by a weightlifter when lifting a 60-kg barbell a vertical distance of 1.2 m in a time interval of 1.5 s.

Work done

=mgh
= 60 kg * 9.8 m/s² * 1.2 m
= 705.6 j
Power
= work done / time
= 705.6 j / 1.5 s.
= 470 watts (approximately)

The difference may be due to the assumed value of g in the question.

To show that 480 W of power is expended by a weightlifter, we can use the formula for power:

Power = Work / Time

First, let's calculate the work done by the weightlifter. The work is given by the formula:

Work = Force × Distance

The force exerted by the weightlifter can be calculated using the equation F = m × g, where m is the mass of the barbell and g is the acceleration due to gravity. In this case, the mass is 60 kg, and the acceleration due to gravity is approximately 9.8 m/s^2.

So, the force exerted by the weightlifter is:

Force = 60 kg × 9.8 m/s^2 = 588 N

Now we can calculate the work done by the weightlifter:

Work = Force × Distance = 588 N × 1.2 m = 705.6 Joules

Finally, we can calculate the power expended by the weightlifter using the formula:

Power = Work / Time = 705.6 J / 1.5 s = 470.4 Watts

Therefore, we have shown that 480 W of power is expended by the weightlifter when lifting a 60-kg barbell a vertical distance of 1.2 m in a time interval of 1.5 s.