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.
power=work/time=mgh/time=60*9.8*1.2/1.5
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.
To show that 480 W of power is expended by a weightlifter lifting a 60-kg barbell a vertical distance of 1.2 m in a time interval of 1.5 s, we need to calculate the power using the formula:
Power (P) = Work (W) / Time (t)
First, let's calculate the work done by the weightlifter. Work is defined as the force applied on an object multiplied by the distance over which the force is applied. In this case, the weightlifter exerts a force equal to the gravitational force on the barbell, and the barbell is lifted a vertical distance of 1.2 m.
Work (W) = Force (F) × Distance (d)
The force exerted by the weightlifter can be calculated using Newton's second law of motion:
Force (F) = mass (m) × acceleration due to gravity (g)
Where:
mass (m) = 60 kg (mass of the barbell)
acceleration due to gravity (g) = 9.8 m/s²
Force (F) = 60 kg × 9.8 m/s² = 588 N
Now, we can calculate the work:
Work (W) = Force (F) × Distance (d) = 588 N × 1.2 m = 705.6 J
Next, we can use the formula for power to find the rate at which work is done:
Power (P) = Work (W) / Time (t) = 705.6 J / 1.5 s ≈ 470 W
Therefore, the weightlifter expends approximately 470 W (rounded to the nearest whole number) of power while lifting the 60-kg barbell a vertical distance of 1.2 m in a time interval of 1.5 s.