Question

An electron starting from rest has a velocity that increases linearly with the time that is $v = k t$ where $k = 2 m / \sec ^ { 2 }$ The distance travelled in the first 3 seconds will be

• A. 9 m
• B. 16 m
• C. 27 m
• D. 36 m

Answer 1

Answer: (A)

9 m

Answer 2

$x =$ $\int _ { t _ { 1 } } ^ { t _ { 2 } } v d t$ $= \int _ { 0 } ^ { 3 } 2 t d t = 2 \left[ \frac { t ^ { 2 } } { 2 } \right] _ { 0 } ^ { 3 } =$ 9 m.