A particle of mass is released from rest at a height of above the ground

PHYSICS · Single correct · A Level · Physics · Mechanics and materials · Mechanics and materials

Problem

A particle of mass

1\,\text{kg}

is released from rest at a height of

20\,\text{m}

above the ground. During the fall it experiences a constant air resistance equal to

0.20\,mg

acting upward. Find the speed of the particle when it has fallen

10\,\text{m}

. (Take

g = 9.8\,\text{m s}^{-2}

.) (a)

14.0\,\text{m s}^{-1}

(b)

15.3\,\text{m s}^{-1}

(c)

12.5\,\text{m s}^{-1}

(d)

9.9\,\text{m s}^{-1}