An observer and a vehicle, both start moving together from rest (towards the right) with acceleration 5 m s - 2 and 2 m s - 2 , respectively. There is a 2 kg block on the floor of the vehicle and coef

Question

An observer and a vehicle, both start moving together from rest (towards the right) with acceleration $5 m s^{- 2}$ and $2 m s^{- 2}$ , respectively. There is a $2 kg$ block on the floor of the vehicle and coefficient of friction is $μ = 0. 3$ between their surface. Then the work done by the frictional force on the $2 kg$ block observed by the running observer, during the first $2$ seconds of the motion

TestHub · Accepted Answer

f limiting = μ mg = 0 . 3 × 2 × 1 0 = 6 N Force needed for acc. of 2 m s - 2 F = m a = 4 N So friction force static, f = 4 N Displacement w.r.t. observer in t = 2 sec. is S = u rel t + 1 2 a rel t 2 = 0 + 1 2 - 3 × 4 = - 6 m W = f → . S → = 4 - 6 = - 2 4 J

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