Solution: (a) The net force is zero because car is travelling with same speed that is 60 miles per hour or there is no acceleration.
(b) Mass of object is 10 kg
Acceleration is 2 m/s², thus force can be calculated as follows:
F=m×a
Here, m is mass of object and a is its acceleration thus,
F=10 kg×2 m/s²
=20 kg m/s²
Here, 1 N=1 kg m/s²
Thus, F=20 N
(c) Force on object is 17 N and its acceleration is 1.5 m/s².
Mass of the object can be calculated as follows:
m=\frac{F}{a}
thus,
m=\frac{17 N}{1.5 m/s^{2}}=11.33 (\frac{N}{m/s^{2}})
Here, 1 N=1 kg m/s²
Thus,
m=11.33 kg