A stone is thrown horizontally with velocity u. The velocity of the stone 0.5 s later is 3 u / 2. The value of u is

Question

A stone is thrown horizontally with velocity u. The velocity of the stone 0.5 s later is 3 u / 2. The value of u is (A) 2.2 m / s (B) 3.3 m / s (C) 4.4 m / s (D) 1.1 m / s

Tardigrade Admin · Accepted Answer

At t=0.5 s, the vertical component of velocity is vt=g t=g(0.5)=(g/2)=4.9 m / s Hence at t=0.5 s , we have √vt2+u2=(3 u/2) or (4.9)2+u2=(9 u2/4) or 5 u2=4 ×(4.9)2 or u2=(0.8)(4.9)2 or u=(4.9) √0.8=4.4 m / s

Q. A stone is thrown horizontally with velocity u. The velocity of the stone 0.5 s later is 3u/2. The value of u is

2.2 m / s

3.3 m / s

4.4 m / s

1.1 m / s

At t=0.5s, the vertical component of velocity is vt​=gt=g(0.5)=2g​=4.9m/s Hence at t=0.5s, we have vt2​+u2​=23u​ or (4.9)2+u2=49u2​ or 5u2=4×(4.9)2 or u2=(0.8)(4.9)2 or u=(4.9)0.8​=4.4m/s

Q. A stone is thrown horizontally with velocity $u$ . The velocity of the stone 0.5 s later is $3 u /2$ . The value of $u$ is