Question

23. An arrow is shot straight up into the air at avelocity of 90 m/s. Assuming air resistancehas no effect, what is the velocity of thearrow after 6 seconds?A. 31.2 m/sB. O m/sC.-43.9 m/sD. 43.9 m/s

Answer 1

Given data:

* The initial velocity of the arrow is 90 m/s.

* The time taken by the arrow is 6 seconds.

* The acceleration of the arrow while moving in the upward direction is,

$g=-9.8ms^{-2}$

Solution:

By the kinematics equation, the final velocity of the arrow in terms of the initial velocity, acceleration, and time is,

$v-u=gt$

where v is the final velocity, u is the initial velocity, g is the acceleration due to gravity and t is the time taken,

Substituting the known values,

$\begin{gathered} v-90=-9.8\times6 \\ v-90=-58.8 \\ v=-58.8+90 \\ v=31.2\text{ m/s} \end{gathered}$

Thus, the final velocity of the arrow is 31.2 m/s.

Hence, option A is the correct answer.