Question

a 15 kg block is sliding across a surface with an initial velocity of 0.5 m/s . calculate the average friction force if it comes to rest within a distance of 1.7m​

Answer 1

Using the work-energy theorem, the total work done on the block as it slides to rest is the negative work performed by friction. If the average magnitude of friction is
`F`, then

`W_(\rm total) = \Delta K \\\\ \implies -F(1.7\,\mathrm m) = 0 - \frac12(15\,\mathrm{kg})\left(0.5(\rm m)/(\rm s)\right)^2 \\\\ \implies F = 1.875\,\mathrm N \approx \boxed{1.9\,\mathrm N}`