Question

A ball is thrown from height H and a ball hit the floor with velocity 10(i-j)

Answer 1

Answer:

Magnitude of initial velocity is $11.04 m/s$

Explanation:

Final velocity 10(i-j)

The horizontal component of the velocity of projection remains unaltered during the flight of the projectile.

Now consider that the vertical component of velocity of projection is  $u\hat{j}$,

the velocity of projection will be $10\hat{i}-u\hat{j}$ m/s

Applying equation of kinematics for the change in vertical component of velocity during time of flight  is 1.5 s

$v=u+at\\-10=u-9.8 \times 1.5\\u= 4.7 m/s$

Hence initial velocity is $10\hat{i}+4.7 \hat{j} m/s$

Magnitude of initial velocity is

$=\sqrt{10^2+4.7^2}\\ =11.04 m/s$