A particle accelerates uniformly from 10 km/hr to 20 km/hr with acceleration of 2 km/hr2. The total time it takes is:
Correct answer: D. 5 hr
- A. 20 hr
- B. 10 min
- C. 10 hr
- D. 5 hr
Explanation
The formula for acceleration is a = ∆v/∆t, where ∆v is the change in velocity and ∆t is the change in time. Rearranging the formula to solve for ∆t, we have ∆t = ∆v/a. Here, the change in velocity (∆v) is (20 km/hr - 10 km/hr) = 10 km/hr, and the acceleration (a) is 2 km/hr2. Plugging these values into the formula gives ∆t = 10 km/hr / 2 km/hr2 = 5 hr. Thus, the correct answer is 5 hr. The other options, 20 hr, 10 min, and 10 hr, do not match the calculation and are therefore incorrect.
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