Question

Which requires more work: lifting a 10 𝑘𝑔 sack of rice to a vertical distance of 2.0 𝑚 or lifting a 5 𝑘𝑔 sack of rice to a vertical distance of 4.0 m

Answer 1

Let's find the work done in both cases:

a) lifting a 10 𝑘𝑔 sack of rice to a vertical distance of 2.0 𝑚:

$$W=Fh=mgh=10\ kg\times9.8\ \dfrac{m}{s^2}\times2\ m=196\ J.$$

b) lifting a 5 𝑘𝑔 sack of rice to a vertical distance of 4.0 m:

$$W=Fh=mgh=5\ kg\times9.8\ \dfrac{m}{s^2}\times4\ m=196\ J.$$

As we can see from the calculations, both cases require the same amount of work.