A boxcar of mass 125 tons at rest becomes uncoupled on a 2.0° grade.If the track is considered to be frictionless,what speed does the boxcar have after 9.0 seconds?
A)4.0 m/s
B)0.038 m/s
C)31 m/s
D)3.1 m/s
E)0.31 m/s

Question

Quizplus · Accepted Answer

The acceleration of the boxcar can be calculated using the component of gravitational acceleration along the incline: $ a = g \sin(\theta) $. With $ g = 9.8 \, \text{m/s}^2 $ and $ \theta = 2.0^\circ $, $ a \approx 9.8 \times \sin(2.0^\circ) \approx 0.342 \, \text{m/s}^2 $. Using $ v = at $, the speed after 9 seconds is $ v = 0.342 \times 9 \approx 3.1 \, \text{m/s} $.

A Boxcar of Mass 125 Tons at Rest Becomes Uncoupled