Solve Newton's 3rd Law Homework: Mass of Block on Left

[mcryder16]

Homework Statement

The 120.8 kg block in FIGURE takes 5.87 s to reach the floor after being released from rest. What is the mass of the block on the left? (h=1.05 m.)

Homework Equations

Any ideas of how to do this problem?

The Attempt at a Solution

 

[Pengwuino]

You need to give us way more information about this problem to receive any advice.

 

[nlightner]

To solve this problem, we can use Newton's third law, which states that for every action, there is an equal and opposite reaction. In this case, the action is the force of gravity pulling the block downward, and the reaction is the force of the floor pushing the block upward.

We can use the equation F=ma, where F is the force, m is the mass, and a is the acceleration. Since the block is initially at rest, the initial velocity (v0) is 0. We also know that the final velocity (v) is 0, since the block reaches the floor and stops moving.

We can rearrange the equation to solve for mass: m=F/a. We can calculate the force of gravity using the equation F=mg, where g is the acceleration due to gravity (9.8 m/s^2). Plugging in the values, we get:

F=mg= (120.8 kg)(9.8 m/s^2)= 1182.24 N

We can then use the equation a=Δv/Δt, where Δv is the change in velocity and Δt is the time it takes for the block to reach the floor. Plugging in the values, we get:

a=Δv/Δt= (0 m/s - 0 m/s)/(5.87 s)= 0 m/s^2

Now we can substitute these values into our equation for mass:

m=F/a= (1182.24 N)/(0 m/s^2)= undefined

This means that the mass of the block on the left is undefined. This could be due to a few reasons:

1. The block on the left may have a mass of 0 kg, meaning it is not present or does not contribute to the motion of the block on the right.

2. The block on the left may have a mass that is too small to affect the motion of the block on the right significantly.

3. There may be other external forces acting on the system that are not accounted for in this problem.

In order to get a more accurate answer, we would need more information about the system and the forces acting on it. This could include the masses of other objects, the friction between the blocks and the floor, and any other external forces.