Question

An applied force of 50 N is used to accelerate an object to the right across a frictional surface. The object encounters 10 N of friction. Use the diagram to determine the normal force, the net force, the mass, and the acceleration of the object. (Neglect air resistance.)​

Answer 1

$\tt\implies$To simplify calculations, an approximated value of g is often used - 10 m/s/s.

$\tt\implies$Answers obtained using this approximation are shown in parenthesis.

 

$\tt\implies$ $F_{norm}$= 80 N; m = 8.16 kg; $F_{net}$ = 40 N, right; a = 4.9 m/s/s, right

$\tt\implies$( $F_{norm}$ = 80 N; m = 8 kg; $F_{net}$= 40 N, right; a = 5 m/s/s, right )

$\tt\implies$Since there is no vertical acceleration, normal force = gravity force.

$\tt\implies$The mass can be found using the equation $F_{grav}$ = m • g.

$\tt\implies$The $F_{net}$ is the vector sum of all the forces: 80 N, up plus 80 N, down equals 0 N. And 50 N, right plus 10 N, left = 40 N, right.

$\tt\implies$Finally, a = $F_{net}$ / m = (40 N) / (8.16 kg) = 4.9 m/s/s.