The wooden block is moved on a horizontal surface using a spring with a hardness of 50 N / m.

The wooden block is moved on a horizontal surface using a spring with a hardness of 50 N / m. Determine the mass of the block if it is known that the spring has lengthened by 2.5 cm and the friction force is 20% of the entire body.

k = 50 N / m.

x = 2.5 cm = 0.025 m.

Ftr = 0.2 * R.

g = 9.8 m / s2.

m -?

According to Newton’s first law, a body moves uniformly in a straight line if no forces act on it or the action of forces is compensated.

In the horizontal direction, the force F with which the bar is pulled is equal to the friction force Ffr: Ffr = F.

F = k * x.

We express the weight of the bar P by the formula: P = m * g.

Ftr = 0.2 * P = 0.2 * m * g.

0.2 * m * g = k * x.

The formula for determining the mass of the bar m will be: m = k * x / 0.2 * g.

m = 50 N / m * 0.025 m / 0.2 * 9.8 m / s2 = 0.64 kg.

Answer: the bar has a mass of m = 0.64 kg.