# Tom and Jerry push on the 3 m diameter merry-go-round

• BrownBoi7
In summary, Tom and Jerry push on a 3 m diameter merry-go-round. Tom exerts a force of 40 N and Jerry exerts a force of 35.2 N. The net torque on the merry-go-round is -0.05 Nm if both forces are in the same direction, and 104 Nm if Jerry reverses the direction of his force by 180 degrees without changing the magnitude.
BrownBoi7
Tom and Jerry both push on the 3 m diameter merry-go-round shown in the figure attached.

(a) If Tom pushes with a force of 40 N and Jerry pushes with a force of 35.2 N, what is the net torque on the merry-go-round?

(b) What is the net torque if Jerry reverses the direction by 180 degrees without changing the magnitude of his force?

My attempt:
FT = Force exerted by Tom = 40 N
FJ = Force exerted by Jerry = 35.2 N

T = Torque = RF sinΘ

TT = 1.5 m * 40 N * sin 60 = 1.5 m * 40 N * -0.304 = -18.28 Nm
TJ = 1.5 m * 35.2 N * sin 80 = 1.5 m * 35.2 N * -0.993= --52.43 Nm

(a) Net T= -18.28 Nm + (- 52.43 Nm) = -70.71 Nm

(b) When Jerry reverses,
Net T = -18.28 Nm - (-52.43 Nm) = 34.15 Nm

My answers didn't match my professor's answers. I believe I went about it the right way. Could somebody please point out where I messed up?

Thanks!

#### Attachments

• tj.JPG
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I think it's just a problem with your signs. For your torques, you solved both of them to be negative, but that can't be since they push the merry-go-round in different directions. Check that, and you should be good.

Are my values for sin 60 and sin 80 right?

Aren't they both going clockwise? Figure never told me which guy is going which direction.

BrownBoi7 said:
Are my values for sin 60 and sin 80 right?

Aren't they both going clockwise? Figure never told me which guy is going which direction.
After you change your sine and sign, it should be obvious from inspection based on the given direction and location of the forces as to which force tends to rotate the object clockwise and which force tends to rotate it counterclockwise. The net torque is how much cw or ccw?

TT = 1.5 m * 40 N * sin 60 = 1.5 m * 40 N * 0.866 = 51.96 Nm
TJ = 1.5 m * 35.2 N * sin 80 = 1.5 m * 35.2 N * 0.985= 52.008 Nm

So, Tom's going clockwise and Jerry anticlockwise?

(a) 51.96 Nm - 52.008 Nm = -0.048 Nm
(b) 51.96 Nm + 52.008 Nm = 103.968 Nm

Are the right now?

BrownBoi7 said:
TT = 1.5 m * 40 N * sin 60 = 1.5 m * 40 N * 0.866 = 51.96 Nm
51.9970 N-m cw or ccw (minus or plus)?
TJ = 1.5 m * 35.2 N * sin 80 = 1.5 m * 35.2 N * 0.985= 52.008 Nm
51.9615 N-m cw or ccw(minus or plus)?
So, Tom's going clockwise and Jerry anticlockwise?
The merry-go-round is free to totate about the black dot at its center. So when tom pushes it on its left hand side as shown, will the thing tend to spin in the direction of a clock's hands cw as viwed from your screen or the other way ccw?
(a) 51.96 Nm - 52.008 Nm = -0.048 Nm
make math correction and round off to 2 decimal places...what direction (cw or ccw) does the minus sign indicate?
(b) 51.96 Nm + 52.008 Nm = 103.968 Nm
ok, round it off, but what direction does the plus sign indicate?

## What is the purpose of the "Tom and Jerry push on the 3 m diameter merry-go-round" experiment?

The purpose of this experiment is to observe and analyze the effects of a constant force applied to a rotating object, specifically a 3 m diameter merry-go-round. By using the characters of Tom and Jerry, this experiment can also be used as a fun and engaging way to teach children about physics and rotational motion.

## What is the independent variable in the "Tom and Jerry push on the 3 m diameter merry-go-round" experiment?

The independent variable in this experiment is the force applied by Tom and Jerry on the merry-go-round. This can be varied by changing the strength of the push or the direction of the push.

## What is the dependent variable in the "Tom and Jerry push on the 3 m diameter merry-go-round" experiment?

The dependent variable in this experiment is the rotational motion of the merry-go-round. This can be measured by the speed of rotation, the distance traveled, or the angular displacement.

## How does the mass of the merry-go-round affect the results of the "Tom and Jerry push on the 3 m diameter merry-go-round" experiment?

The mass of the merry-go-round can affect the results of the experiment by changing the inertia of the object. A heavier merry-go-round will have a greater resistance to changes in its rotational motion, while a lighter one will be easier to rotate. This can impact the speed, distance, and angular displacement of the merry-go-round in response to the applied force.

## What other factors can influence the results of the "Tom and Jerry push on the 3 m diameter merry-go-round" experiment?

Other factors that can influence the results of this experiment include the friction between the merry-go-round and the ground, the shape and surface of the merry-go-round, and any external forces acting on the object. These factors should be controlled or taken into consideration when analyzing the data from the experiment.

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