SAT Subject Physics Practice Question 12: Answer and Explanation
3. A frictionless inclined plane of length 20 m has a maximum vertical height of 5 m. If an object of mass 2 kg is placed on the plane, which of the following best approximates the net force it feels?
A. 5 N
B. 10 N
C. 15 N
D. 20 N
E. 30 N
Correct Answer: A
The net force that the object feels on the inclined plane is mg sinθ, the component of the gravitational force that is parallel to the ramp. Since sin θ = (5 m)/(20 m) = 1/4, we have Fnet = (2 kg)(10 N/kg)() = 5 N.