A car covers the first 120 m of a 360 m journey at 10 m s⁻¹. The remaining 240 m is covered in two equal time intervals at 20 m s⁻¹ and 40 m s⁻¹. Find the average speed in m s⁻¹.
Physics · Kinematics Part-1 (one dimension) · Distance,Displacement ,Avg speed and Avg velocity
JEE Mains NEET

Question

A car covers the first 120 m of a 360 m journey at 10 m s⁻¹. The remaining 240 m is covered in two equal time intervals at 20 m s⁻¹ and 40 m s⁻¹. Find the average speed in m s⁻¹.

G1 Physics · Accepted Answer

First 120 m: t₁ = 120/10 = 12 s. Let each of the two equal remaining intervals be τ. 20τ + 40τ = 240 ⇒ 60τ = 240 ⇒ τ = 4 s. Total time = 12 + 4 + 4 = 20 s. Average speed = 360/20 = 18 m s⁻¹.