How Do You Calculate Normal Force for a Cup and Saucer on a Table?

[Snape1830]

1. A cup and saucer rest on a table top. The cup has mass of 0.176 kg and the saucer 0.165 kg. Calculate the magnitude of the normal force a). the saucer exerts on the cup and b). the table exerts on the saucer.



Too be honest I really don't know the equation. I think it might be ΣF=m*a but I'm not sure. And if that is the formula, I do not know how to proceed.

 

[trulyfalse]

Start with a free body diagram. The saucer and cup are not moving upwards or downwards, so Fn=Fg.

 

[Snape1830]

I still don't understand how to find part b. Part a was 1.7 N ($\SigmaF=0.176(9.8)$
So I got part a down, but I can't figure out how to do part b. I tried finding the force due to gravity, and then did Normal force-force due to gravity = ma. That didn't work.

 

[Snape1830]

Never mind, I figured it out!

 

[asteriatic]

I can help you with finding the normal force in this scenario. The normal force is the force exerted by a surface on an object in contact with it, perpendicular to the surface. In this case, the cup and saucer are in contact with the table top, and therefore the table top exerts a normal force on them.

To calculate the normal force, we can use Newton's second law, ΣF=ma, as you mentioned. The key is to identify all the forces acting on the objects and their respective directions. In this case, the only external force acting on the cup and saucer is the force of gravity, which is directed downwards. Therefore, the normal force must be equal in magnitude but opposite in direction to the force of gravity.

a) To find the normal force exerted by the saucer on the cup, we can use the equation ΣF=ma, where a is the acceleration due to gravity, which is approximately 9.8 m/s^2. We know the mass of the cup is 0.176 kg, so the equation becomes:

ΣF = (0.176 kg)(9.8 m/s^2) = 1.73 N

Therefore, the magnitude of the normal force exerted by the saucer on the cup is 1.73 N.

b) To find the normal force exerted by the table on the saucer, we can use the same equation, ΣF=ma, but this time the mass we use is the total mass of the cup and saucer, which is 0.176 kg + 0.165 kg = 0.341 kg. The equation becomes:

ΣF = (0.341 kg)(9.8 m/s^2) = 3.34 N

Therefore, the magnitude of the normal force exerted by the table on the saucer is 3.34 N.

I hope this helps you understand how to find the normal force in this scenario. It's important to remember to always consider all the forces acting on the object and their respective directions in order to accurately calculate the normal force.