Question

a 12-kg block is pulled by a string at a 30 degree angle. if the string exerts a 50 n force, the block accelerates at 4.13 m/s2. what is the frictional force and normal force exerted on the block?

Answer 1

Let, frictional force is f and normal force is N.

Balancing horizontal forces :

$50cos \ 30^o - f = 12 \times 4.13\\\\f = 50cos \ 30^o - 49.56\\\\f = -6.26\ N$

Also, balancing vertical forces, we get :

$N = mg + 50sin \ 30^o\\\\N =( 12\times 9.8 ) + (50\times sin \ 30^o)\\\\N = 142.6\ N$

Therefore, the frictional force and normal force is -6.26 N and 142.6 N.