Question

A block of 100 g is sliding on a horizontal concrete floor under the action of a constant force of 5N with a velocity of 80m/s in 8 s.Find the magnitude of frictional force is 4N.Can u explain how?

Answer 1

From the velocity time graph we can note:-

Final velocity= 80m/s

Initial velocity= 0m/s

Time= 8s

Acceleration= (v-u)/t                      = (80m/s -0m/s) ÷8s                 = 10m/s^2

Mass of the block= 100g=100/1000kg                               = 0.1 kg

Force= mass × acceleration

Force= 0.1 kg × 10m/s^2

Force= 1 N

Constant force - Frictional force= Net force

5N- Frictional force= 1N

-Frictional Force= 1N - 5N

- Frictional Force = -4N

Frictional Force= 4N