A man weighing 80 kg is standing in a trolley weighing 320 kg . The trolley is resting on frictionless horizontal rails. If the man starts walking on the trolley with a speed of 1 m s- 1 , then after 4 s , his displacement relative to the ground will be

Question

A man weighing 80 kg is standing in a trolley weighing 320 kg . The trolley is resting on frictionless horizontal rails. If the man starts walking on the trolley with a speed of 1 m s- 1 , then after 4 s , his displacement relative to the ground will be (A) 5 m (B) 4.8 m (C) 3.2 m (D) 3 m

Tardigrade Admin · Accepted Answer

Displacement of trolley w.r.t. ground, x=(m L/m + M)=(80 × 4/80 + 320)=0.8 m ∴ m1x1=m2x2 ⇒ 320× 0.8=80x2 ⇒ x2=3.2m

Q. A man weighing $80 k g$ is standing in a trolley weighing $320 k g$ . The trolley is resting on frictionless horizontal rails. If the man starts walking on the trolley with a speed of $1 m s^{- 1}$ , then after $4 s$ , his displacement relative to the ground will be

$5 m$

$4.8 m$

$3.2 m$

$3 m$

Displacement of trolley w.r.t. ground,
$x = \frac{m L}{m + M} = \frac{80 \times 4}{80 + 320} = 0.8 m$
$∴ m_{1} x_{1} = m_{2} x_{2}$
$\Rightarrow 320 \times 0.8 = 80 x_{2}$
$\Rightarrow x_{2} = 3.2 m$

Q. A man weighing 80kg is standing in a trolley weighing 320kg . The trolley is resting on frictionless horizontal rails. If the man starts walking on the trolley with a speed of 1ms−1 , then after 4s , his displacement relative to the ground will be

5m

4.8m

3.2m

3m