Physics Circle home Student Login

Home›Chapters›Projectile Motion PYQs›Time of Flight, Maximum Height & Range›Question 17

JEE Main 2023 (11 Apr, Shift 1) · Time of Flight, Maximum Height & Range

Time of Flight, Maximum Height & Range question from JEE Main 2023 (11 Apr, Shift 1)

Q17JEE Main 2023 · 11 APR · SHIFT 1Medium

Time of Flight, Maximum Height & Range

A projectile fired at 30∘30^\circ to the ground is observed to be at same height at time 3 s3\text{ s} and 5 s5\text{ s} after projection, during its flight. The speed of projection of the projectile is ___________ m s−1\text{m s}^{-1}. (Given g=10 m s−2g = 10\text{ m s}^{-2})

Numerical answer type. Work it out, then open the answer.

Show answer and solution

Answer: 80

  1. Same height at t1t_1 and t2t_2 means time of flight T=t1+t2=3+5=8 sT = t_1 + t_2 = 3 + 5 = 8\text{ s}.
  2. T=2usin⁡θg⇒8=2usin⁡30∘10=u10T = \frac{2u\sin\theta}{g} \Rightarrow 8 = \frac{2u\sin 30^\circ}{10} = \frac{u}{10}
  3. u=80 m s−1u = 80\text{ m s}^{-1}
Report a mistake

More questions on Time of Flight, Maximum Height & Range