Question

3a. With a BALL of mass 10 kg you compress a SPRING of k = 1.00 x 106 kg s-2 by Dx = 10 cm. How HIGH does the BALL fly upward when you release it? B. A person of mass 60 kg jumps from a height of 3 m. She lands on her feet but her knee joints each compress by 0.5 cm. What force did she put on her knees?

Answer 1

PART A:

Given that:

Mass of the ball, m = 10 kg

Spring constant, K = 1 x 10⁶ N/m

Spring compression, D = 10 cm = 0.1 m

Apply law of conservation of energy:

That is the height reached by the ball is 51 m.

PART B:

Apply Work - energy theorem:

Work done by the force (F) on knee = work done by gravity (U)

That is force on knees = 353388 N.