# Net Force on Top Block: 115.2 N

• wolves5
In summary, the top block is being accelerated upwards at a rate of 3.2 m/s2 by a force of 115.2 N applied to the bottom block.
wolves5
Three blocks are bring accelerated upwards at 3.2m/s2, by a force applied to the bottom block as shown in the figure. The mass of the bottom block is 12kg, the mass of the middle block is 24 kg, and the top block is 36 kg. What is the net force on the top block?

a.44.8 N
b.67.2 N
c.115.2 N
d.240.0 N

I don't know how to start this problem. Do I just do F=(36)(3.2) and get C as my answer?

You're correct. The best way to handle this type of problem is to draw a picture (free body diagram) of the top block.

The top block has two forces acting on it.
Force 1: The middle block is forcing the top block upward.
Force 2: Gravity is pulling the top block downward.

The summation of forces in the vertical direction gives:
FSecond Block - FGravity = FNet

In many problems, you would be given the force of the Second Block and calculate gravitational force to find net force as shown in the equation above. Because we've been given the mass of the top block along with it's acceleration we can calculate the net force directly and forget the above equation:
FNet = m a = (36) (3.2 m/s2) = 115.2 N

## 1. What is the definition of "Net Force"?

Net force is the combination of all the forces acting on an object, taking into account both the magnitude and direction of each force.

## 2. How is Net Force calculated for the top block in this scenario?

In order to calculate the net force on the top block, you would need to add up all the forces acting on the block, including any external forces, and take into account their respective magnitudes and directions.

## 3. What is the unit of measurement for Net Force?

The unit of measurement for net force is Newtons (N), which is equivalent to 1 kg*m/s^2.

## 4. Can Net Force be negative?

Yes, net force can be negative if the forces acting on an object are in opposite directions. This indicates that there is a net force acting in the opposite direction of the object's motion, causing it to slow down or change direction.

## 5. How does Net Force affect an object's motion?

According to Newton's Second Law of Motion, the net force on an object is directly proportional to its acceleration. This means that a larger net force will result in a greater acceleration, while a smaller net force will result in a smaller acceleration. Additionally, the direction of the net force will determine the direction of the object's acceleration.

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