Question

Two blocks a and b ($m_a>m_b$) are pushed for a certain distance along a frictionless surface. how does the magnitude of the work that a does on b compare to the magnitude of the work that b does on a?

Answer 1

Answer:

the magnitude of the work done by the two blocks is the same.

Explanation:

The work done by block a on block b is given by:

$W_a = F_a d$

where Fa is the force exerted by block a on block b, and d is the distance they cover.

The work done by block b on block a is given by:

$W_b = F_b d$

where Fb is the force exerted by block b on block a, and d is still the distance they cover.

For Newton's third law, the force exerted by block a on block b is equal to the force exerted by block b on block a, therefore

$F_a = F_b$

and so

$W_a=W_b$