Answer: 910 N.
- A 490 N
- B 630 N
- C 700 N
- D 910 N
Correct answer: D. 910 N
Explanation: N - mg = ma. N = m(g+a) = 70 x 13 = 910 N. Person feels heavier when elevator accelerates up.
Free-body diagram of a block on an incline: weight (mg) resolves into mg sinθ along the slope and mg cosθ into the slope, balanced by the normal force N and friction f.
Concept context
Newton's three laws, friction, circular motion, and free body diagrams.