Question

a block of 5 kg kept on a smooth surface at rest is acted by an external vertical F if the external force displaced the block by 25m where it's velocity becomes 8m/s then work done by external force

Answer 1

u=0
v=8m/s
a=?
s=25m
${v}^{2} = {u}^{2} + 2as$
${8}^{2} = {0}^{2} + 2 \times a \times 25$
$64 = 50 \times a$
$\frac{64}{50 } = a$
$\frac{32}{25} = a$
$f = ma$
$f = 5 \times \frac{32}{25}$
$f = \frac{32}{5}$
w=fd
w=32/5×25
w=32×5
w=160kg×m/sec2