Question

A body mass 10 kg is moving with a velocity (10i + 10j + 10k) m/s. Find the magnitudes of its momentum
and K.E.
16. Water in a river flowing with a velocity 5 m/sec. Find the energy carried by 10m of water in the river flow.

Answer 1

1.

Momentum$=100\sqrt{3}$ kg-m/s

K.E  =1500 J

Step-by-step explanation:

Given, a body mass 10 kg is moving with a velocity $(10\hat{i}+10\hat{j}+10 \hat{k})$ m/s.

$v^2 = 10^2+10^2+10^2$  = 300 and $v = 10\sqrt{3}$

Momentum= mass × velocity  

                 = $10 \times 10\sqrt{3}$    kg-m/s

                 $=100\sqrt{3}$ kg-m/s

Therefore K.E = $\frac{1}{2} \times m \times v^2$

                        $=\frac{1}{2} \times 10 \times 300$ j

                        =1500 J

2.

Water in a river flowing with a velocity 5 m/s.

Therefore K.E = m× g × h

                      $=m \times 9.8 \times 5$ j [ m is the mass of the water ]

                      =49m  J

Therefore the energy carried by 10 m .of water in the river flow =49m j