Question

A weightlifter curls a 35 ${\rm kg}$ bar, raising it each time a distance of 0.70 ${\rm m}$ .

How many times must he repeat this exercise to burn off the energy in one slice of pizza? Assume 25% efficiency.

1 slice of pizza = 300C = 1260kJ

Express your answer using two significant figures.

Answer 1

The weightlifter will use the 1260 kJ (at 25% efficiency)

(1.26 10 ^6J) (0.25) = n x 35 x 9.8 x 0.70

Solving for n gives 1311.9 times   

(energy from pizza) (efficiency) nmgAy