Question

A model rocket accelerates upward from the ground with a constant acceleration, reaching a height of 50 m in 8 s.What is the speed (in m/s) at a height of 50 m?A: 1.07×101 B: 1.25×101 C: 1.46×101 D: 1.71×101 E: 2.00×101

Answer 1

Answer:

The  value is  $v = 12.5 \ m/s$

Explanation:

From the question we are told that

    The  height is  $h = 50 \ m$

    The  time taken is  $t = 8 \ s$

   

From the equation of motion we have  that

 $s = ut + \frac{1}{2} * a * t^2$

Here u = 0  because the rocket started at rest

  $50 = 0 + \frac{1}{2} * a * 8^2$

=>   $a = \frac{100}{64}$

=>    $a = 1.5625 \ m/s^2$

Also from the kinematic equation we have that

    $v = u + at$

=>  $v = 0 + (8 * 1.5625)$

=>   $v = 12.5 \ m/s$