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MHT CET · Physics · Motion In Two Dimensions

A stone is projected vertically upwards with velocity ' \(\mathrm{V}\).
Another stone of same mass is projected at an angle of \(60^{\circ}\) with the vertical with the same speed (V). The ratio of their potential energies at the highest points of their journey, is

  1. A 1:1
  2. B 4:1
  3. C 3:2
  4. D 2:1
Verified Solution

Answer & Solution

Correct Answer

(B) 4:1

Step-by-step Solution

Detailed explanation

Maximum height, \(\mathrm{h}=\frac{\mathrm{u}^2 \sin ^2 \theta}{2 \mathrm{~g}}\)
For the first stone \(\theta=90^{\circ}, \sin 90^{\circ}=1\)
\(\therefore \mathrm{h}_1=\frac{\mathrm{u}^2}{2 \mathrm{~g}}=\frac{\mathrm{V}^2}{2 \mathrm{~g}}\)
For the second stone, \(\mathrm{h}_2=\frac{\mathrm{v}^2 \sin ^2 30^{\circ}}{2 \mathrm{~g}}=\frac{\mathrm{V}^2}{8 \mathrm{~g}}\) The masses are same. Hence ratio of potential energies
\(\frac{\mathrm{U}_1}{\mathrm{U}_2}=\frac{\mathrm{h}_1}{\mathrm{~h}_2}=4\)