A 4 kg rock is suspended by a massless string from one end of a 7 m measuring stick. What is the weight of the measuring stick if it is balanced by a support force at the 1 m mark? The acceleration of gravity is 9.81 m/52 Answer in units of N.

Answer 1

To solve this problem, we need to analyze the forces acting on the measuring stick.

First, let's calculate the weight of the rock. The weight can be calculated using the formula:

Weight = mass * gravity

Weight = 4 kg * 9.81 m/s^2

Weight = 39.24 N

Since the measuring stick is balanced, the total torque on the measuring stick must be zero. The torque due to the weight of the rock can be calculated as:

Torque = weight * distance

Torque = 39.24 N * 7 m

Torque = 274.68 N·m

We want to find the support force at the 1 m mark. The distance from the support force to the center of the measuring stick is 6 m (7 m - 1 m). Therefore, the torque due to the support force can be calculated as:

Torque = support force * distance

Torque = support force * 6 m

Since the measuring stick is balanced, the torque due to the support force must be equal and opposite to the torque due to the weight of the rock:

274.68 N·m = support force * 6 m

Solving for the support force:

support force = 274.68 N·m / 6 m

support force = 45.78 N

Therefore, the weight of the measuring stick is 45.78 N.