# General conceptual physics help

1. What is the acceleration of a 20kg sled as it is pulled across the ground with an applied force of 50N? The force of friction working against the sleds motion is 30N.

2. A railroad deisel engine coasting at 10km/h runs into a stationary flatcar. The deisel weighs 4 times as much as the flatcar. Assuming the cars couple together, how fast are they moving after the collision?

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1. Newton's second law states that the acceleration (a) is the ratio between the *total* force applied on the body (F) to its mass (m):

a=F/m

Here the total force applied on the sled is F=50-30=20N.

Note that when we add forces to find the total net force, we have to take into consideration their directions. If we assume tha the direction of the pulling force is positive, then the direction of the ...

#### Solution Summary

Solution explains how to determine the acceleration of a sled pulled across the ground. Acceleration is also determined for a railroad deisel engine post-collision. Provided are all the necessary steps and equations.