Solve a Physics Problem: Normal Force Calculation for a 38.0kg and 17.0kg Box

In summary, a 38.0 kg box is resting on a table and a 17.0 kg box is placed on top of it. The normal force exerted by the 17.0 kg box on the 38.0 kg box is 168 N. According to Newton's 3rd Law, the normal force exerted by the 38.0 kg box on the 17.0 kg box is also 168 N in the opposite direction.
  • #1
lmf22
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A 38.0 kg box (m1) rests on a table. A 17.0 kg box (m2) is placed on top of the 38.0 kg box. What is the normal force that the 38.0 kg box exerts on the 17.0 kg box.

I found that the normal force of just the 38.0kg box is 372.78N and the normal force of just the 17.0kg box is 166.77N. But I don't know how to figure out the normal force that the 38.0kg box exerts on the 17.0kg box.

any help?
 
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  • #2
The 17.0 kg box exerts a force of 166.77 N on the 38.0 kg box. Therefore, the normal force is _______. <--- figure it out yourself.
 
  • #3
Upward direction : positive; downward direction : negative
[tex]\begin{array}{cc}\\
Consider\ mass\ m_1:\\
Newton's \ 2nd\ Law\\
\sum \vec{F} =m\vec{a}= 0 \ in\ this\ case\\
Fm_2m_1+(-m_2g)=0\\
Fm_2m_1 = m_2g\\
= 17.0*9.81\\
= 168 \ N\\
Fm_2m_1= - Fm_1m_2 : Newton's \ 3rd\ Law\\
\end{array} [/tex]
 

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  • #4
Thank you very much guys. Leong, the picture really helps.
Thanks again.
 

1. What is normal force in physics?

Normal force is the force that an object experiences when it is in contact with a surface. It acts perpendicular to the surface and prevents the object from sinking into the surface.

2. How is normal force calculated?

Normal force is calculated as the product of an object's mass and the acceleration due to gravity. It can also be calculated by using the equation F = ma, where F is the normal force, m is the mass of the object, and a is the acceleration.

3. What is the relationship between normal force and weight?

The normal force is equal to the weight of an object when it is placed on a flat surface and is not accelerating. This means that the normal force and weight are directly proportional to each other.

4. Can the normal force be negative?

Yes, the normal force can be negative in certain situations. For example, if an object is accelerating downwards, the normal force acting on it will be negative, as it is pushing the object into the surface instead of preventing it from sinking into the surface.

5. How does the normal force affect an object's motion?

The normal force does not directly affect an object's motion, as it acts perpendicular to the direction of motion. However, the normal force can indirectly affect an object's motion by influencing its acceleration or by balancing out other forces acting on the object, such as gravity.

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