Question

Car will start moving after time t = .................... second :-

• A. 4
• B. 10
• C. 5
• D. 8

Answer 1

Answer: (C)

5 seconds

Answer 2

The car starts moving when the thrust force overcomes the maximum static friction force. At the point of impending motion, the thrust force equals the friction force. $F_T = F_f(t)$ $40 = 50 - 2t$ $2t = 50 - 40$ $2t = 10$ $t = 5$ seconds. So, the car will start moving after 5 seconds.