Question

A particle moving in a straight line covers half the distance with speed 3 ms^-1. The other half is covered in two equal time intervals with speeds 4.5 ms^-1 and 7.5 ms^-1, respectively. The average speed of the particle during motion is

• A. 4 ms^-1
• B. 5ms^-1
• C. 5.5 ms^-1
• D. 4.8 ms^-1

Answer 1

Answer: (D)

4.8 ms^-1

Answer 2

Here t₁ = $\frac{x}{2 \times 3} = \frac{x}{6}$ ; x₁ = 4.5 t₂

Also x/2 = 7.5 t₂ = x₁ + x₂ = 12t₂

or t₂ = x/24

t = $\frac{x}{24} + \frac{x}{6} = \frac{5x}{24}$

v = $\frac{x}{t} = \frac{24}{5}$ = 4.8 ms^-1