Question

An iron block of mass 5kg is kept in a trolley. if the trolley is being pushed with an acceleration of $5m/s^2$, What will be the force of friction between the block and the trolley surface (Take the coefficient of static friction between the block and the surface to be 0.8).

• A. zero
• B. 5 N
• C. 4 N
• D. 25 N

Answer 1

The correct option is D 25 N

$a_{trolley}=0a_{block}=-5m/s^2{\left(f_s\right)}_{max}=\mu \times 5\times g=0.8\times 5\times 10=40N$

$F_{due}$ to trolley motion on block =$ma=5\times 5=25Nf<{\left(f_s\right)}_{max}$

Block will not move wrt trolley

But force of friction b/w them =$F$

$F=25N$