A worker applying a force of 400 N pushes a trolley with a mass of 0.3 tons.

A worker applying a force of 400 N pushes a trolley with a mass of 0.3 tons. Determine the friction force that acts on the trolley if its acceleration is 0.5 m / s ^ 2.

F = 400 N.

m = 0.3 t = 300 kg.

a = 0.5 m / s ^ 2.

Ftr -?

According to Newton’s 2 law, the resultant of all forces Frav that act on the body is equal to the product of the acceleration of the body a by its mass m: Frav = a * m.

Only 2 forces act on the body in the horizontal direction: the force F, with which the worker pushes the trolley, and the friction force Ffr, which is directed in the opposite direction of the trolley movement, and therefore against the force F.

The resultant Frav of forces will be the difference: Frav = F – Ftr.

F – Ftr = a * m.

Ftr = F – a * m.

Ftr = 400 N – 0.5 m / s ^ 2 * 300 kg = 240 N.

Answer: the friction force Ftr = 240 N. acts on the trolley when moving.