Question

A block of a wood of mass 30 kg accelerating down a concrete slope incined at 45degree . Calculate the acceleration of the block the cofficient of kinitic friction between the wood and the slope is=0.45

Answer 1

Let's say the mass is m. It does not matter
normal force on block = m g cos 45
so friction force up slope = 0.45 m g cos 45
gravity force down slope = m g sin 45
net force down slope = m g (sin 45 - 0.45 cos 45)
F = m a
so
a = g (sin 45 - 0.45 cos 45)
but sin 45 = cos 45 = 0.797
so a = g (0.55*0.707) = .389 g
if on earth g = 9.81m/s^2
then
a = .389*9.81 m/s^2

Answer 2

how car was decelarathing