(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

A 2.7 kg toy locomotive is pulling a 1.2 kg caboose. The frictional force of the track on the caboose is 0.48 N backward along the track. If the train is accelerating forward at 2.7 m/s2, what is the magnitude of the force exerted by the locomotive on the caboose?

2. Relevant equations

F=ma and f=uN (the formula relating friction to normal force)

3. The attempt at a solution

I've found the normal forces and weights and drawn my FBD's (free body diagrams) and realize that the tension is the only force acting on the caboose other than friction...

Am I supposed to add the masses of the objects, and find the force using the acceleration? Do I subtract friction?

I know:

2.7 kg X 2.7 m/s2 = 7.29 N (mass of train times accel.)

1.2 kg X 2.7 m/s2 = 3.24 N (mass of caboose times accel.)

(1.2 kg + 2.7 kg) X 2.7 m/s2 = 10.53 N (both masses combined times accel.)

i also assume friction needs to be subtracted since it acts in the negative direction...but i don't know where to go from here...

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# Homework Help: Train pulling caboose - forces and friction

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