A car with a mass of 2.0 × 10³ kg travels in a straight line at a constant speed on a flat road. Its speed is 15 m/s. At a certain moment (t = 0) it accelerates with a constant acceleration of 2.0 m/s², in the same direction as the velocity. The constant friction force is 2000 N. The forces F1 and F2 exerted by the engine in the first and second segments, respectively, are:
A) F1 = F2 = 2000 N
B) F1 = 30 × 10³ N, F2 = 4000 N
C) F1 = 0, F2 = 4000 N
D) F1 = 0, F2 = 6000 N
E) F1 = 2000 N, F2 = 6000 N
IMAT 2025 · Question 59
Q59 - 1st and 2nd laws of motion
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The correct answer is E) F1 = 2000 N, F2 = 6000 N.
At constant speed nothing is accelerating, so the engine only has to cancel friction: F1 = 2000 N.
When it accelerates: F2 − 2000 = ma = 2000 × 2 = 4000, so F2 = 6000 N.
30 × 10³ is mass times speed (momentum), not a force.
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