Intro to Forces + Newton's Laws Video Lessons

Concept

# Problem: a. Suppose you have a tug of war with a friend who is the same size and weight as you are. You both pull as hard as you can, but neither of you seems to be winning. You move a little one way or the other, but mostly you are just at rest (although sweating some). Compare the magnitude of the force exerted by you on your friend, with the magnitude of the force exerted by your friend on you. Are they the same or different? If they are not the same, which is larger? Why or why not? b. Now you have a tug of war with your kid brother (who is much smaller and lighter than you). Again you both pull hard but end in a standoff with neither of you moving much. In this situation compare the magnitude of the force you exert on your brother with the magnitude of the force he exerts on you. Are they the same or different? If they are not the same, which is larger? Why or why not? c. The next tug of war is still with your kid brother but he is now standing on his skateboard. You can now make him roll across the floor (with a constant speed) when you pull hard. In this situation compare the magnitude of the force you exert on your brother with the magnitude of the force he exerts on you. Are they the same or different? If they are not the same, which is larger? Why or why not?

###### FREE Expert Solution

Newton's second law,

$\overline{){\mathbf{\Sigma F}}{\mathbf{=}}{\mathbf{m}}{\mathbf{a}}}$

The forces exerted on the rope create tension. As such, the tension is equal to the applied force. The tension is transmitted to the opposite end of the rope delivering the applied force.

(a)

Since we are mostly at rest, then a = 0.

Force exerted by me on my friend is F1

Force exerted by my friend on me is F2

The two forces are in opposite directions,

ΣF = F2 - F1 = m(0)

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###### Problem Details

a. Suppose you have a tug of war with a friend who is the same size and weight as you are. You both pull as hard as you can, but neither of you seems to be winning. You move a little one way or the other, but mostly you are just at rest (although sweating some). Compare the magnitude of the force exerted by you on your friend, with the magnitude of the force exerted by your friend on you. Are they the same or different? If they are not the same, which is larger? Why or why not?

b. Now you have a tug of war with your kid brother (who is much smaller and lighter than you). Again you both pull hard but end in a standoff with neither of you moving much. In this situation compare the magnitude of the force you exert on your brother with the magnitude of the force he exerts on you. Are they the same or different? If they are not the same, which is larger? Why or why not?

c. The next tug of war is still with your kid brother but he is now standing on his skateboard. You can now make him roll across the floor (with a constant speed) when you pull hard. In this situation compare the magnitude of the force you exert on your brother with the magnitude of the force he exerts on you. Are they the same or different? If they are not the same, which is larger? Why or why not?

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