Calculating the Tension in Ropes: Jarek, Chris & Michelle

[SPH4U]

Homework Statement

Jarek is motoring along when he spots Chris and Michelle thumbing a ride back to Winnipeg. He hitches them up to two ropes and accelerates westward towards Winnipeg, He pulls with a constant force on a rope which slopes down 30 degrees to Chris's belt. A second rope attached to Chris' belt pulls Michelle's belt. Assume there is no friction force between the level snow-covered road and their skis and that the only motion is their acceleration west. Calculate the tension in the rope joining Michelle and Chris. Mass of Chris = 70Kg; mass of Michelle = 50Kg; mass of Jarek = 60Kg; mass of motorcycle = 100Kg.

Homework Equations

Given:
Chris= 70Kg
Michelle= 50Kg
Jarek= 60Kg + 100Kg; 160Kg
a= constant

Fnet = mg

The Attempt at a Solution

Fnet = mg
= (50Kg)(9.8N/Kg)
= 490N

Fnet = Ff + Fa
Ff = 0
Fa = 490N [W]


It seems a little too simple, can someone please check over my work? Thanks, I really appreciate it.

 

[Doc Al]

Are you given any information about the force exerted or the acceleration?

 

[SPH4U]

Thanks for replying Al; that's what had me thinking...

All the question says about force is that it's constant, it doesn't give any values for acceleration or force.

 

[Doc Al]

Then I don't see how you can answer the question. (Double check that you copied the question exactly as given.)

 

[SPH4U]

That's the exact question. My teacher said that it was possible though =(