Question

A particle is thrown vertically upward with initial velocity of 150m/s. Find the ratio of its speed at t=3s and t=5s. (Take g=10 \(ms^{-2}\))

Answer 1

Given:
Initial velocity u = 150 m/s
g = 10 m/s²
Time t₁ = 3 s, t₂ = 5 s

Step 1: Formula for velocity
v = u − gt

Step 2: Velocity at t = 3 s
v₁ = 150 − 10×3 = 120 m/s

Step 3: Velocity at t = 5 s
v₂ = 150 − 10×5 = 100 m/s

Step 4: Ratio of speeds
v₁ : v₂ = 120 : 100 = 6 : 5

Final Answer: 6 : 5