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.