Question

Chris and Sue are wearing harnesses and are hanging from the ceiling by means of ropes attached to them. They are face to face and push off against each other. Sue has a mass of 52 kg and Chris has a mass of 78 kg. Following the push, Sue reaches a height of 0.65 meters above her starting point. How high does Chris reach?

Answer 1

Answer:

h = 0.288m

Explanation:

Assume

$v_1$ = Speed of Sue

$v_2$ = Speed of Chris immediately after the push

Sue's KE = $\frac{1}{2} mv_1\ ^2 = 26 v_1 \ ^2$

now she swings this is converted into gravitation at PE of

mg n = 52 × 9.8 × 0.65  

= 331.24

$26v_{1}\ ^2$ = 331.24

So, $v_1 = 3.569$

They started at rest by conservation of momentum in case of push off the magnitude of sue momentum and it is equal to the magnitude of Chris momentum in the opposite or inverse direction

$m_1v_1 = m_2v_2$

$52 \times 3.569 = 78 \times v_2$

$v_2 = 2.380$

Chris kt = $\frac{1}{2} \times 78 \times 2.380^2$

= 220.827

220.827 = mgh

So, h = 0.288m