Opted Physics Question

[dlawler2]

Hey guys,

I'm going over the physics opted questions and for the life of me I just can't understand #10. Here's the question:

10. A 50-kg girl pulls a 20-kg wagon with a force
of 10 Newtons. The wagon accelerates at
2 m/s2. What is the force, in Newtons, exerted
BY the wagon ON the girl?

A. 140
B. 100
C. 40
D. 20
E. 10

The answer is 10, but if the force of the cart equaled the force of the girl wouldn't the acceleration be zero? Any help would be greatly appreciated!

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[sportsdude00]

Hey guys,

I'm going over the physics opted questions and for the life of me I just can't understand #10. Here's the question:

10. A 50-kg girl pulls a 20-kg wagon with a force
of 10 Newtons. The wagon accelerates at
2 m/s2. What is the force, in Newtons, exerted
BY the wagon ON the girl?

A. 140
B. 100
C. 40
D. 20
E. 10

The answer is 10, but if the force of the cart equaled the force of the girl wouldn't the acceleration be zero? Any help would be greatly appreciated!

I don't believe acceleration plays a role in this question. From Newton's Third Law, F(girl on wagon)=F(wagon on girl). Thus, the girl pulls with a 10N force, and the wagon pulls back with the same force.

 

[achirum]

I don't believe acceleration plays a role in this question. From Newton's Third Law, F(girl on wagon)=F(wagon on girl). Thus, the girl pulls with a 10N force, and the wagon pulls back with the same force.

Yeah that is correct.