Answer:
The magintude of the acceleration for both objects is 
Explanation:
Drawing a free body diagram on the two boxes we can analyze the system more easily.
we can take the acceleration going up as positive for reference purposes.
for mA let's suppose that is ascending so:
and for mB (descending):
because the two boxes has the same acceleration because they are attached together:
So the magintude of the acceleration for both objects is
in case you dont want to read the answer is B
1 horsepower is equal to 746 W, so the power of the engine is
The power is also defined as the energy E per unit of time t:
Where the energy corresponds to the work done by the engine, which is
. Re-arranging the formula, we can calculate the time t needed to do this amount of work:
The cart comes to rest from 1.3 m/s in a matter of 0.30 s, so it undergoes an acceleration <em>a</em> of
<em>a</em> = (0 - 1.3 m/s) / (0.30 s)
<em>a</em> ≈ -4.33 m/s²
This acceleration is applied by a force of -65 N, i.e. a force of 65 N that opposes the cart's motion downhill. So the cart has a mass <em>m</em> such that
-65 N = <em>m</em> (-4.33 m/s²)
<em>m</em> = 15 kg
