true.A study has been conducted and suggested that indeed improving muscular strength and endurance or exercising can enhance bone density and stop it from declining whether its due to accidents or old age. Also, because this practice is needed to have stronger and more healthier bones, exercising is always a necessity and should be a habit.
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Answer:
1029 Jkg⁻¹
Explanation:
= height dropped by the water falling = 105 m
= acceleration due to gravity = 9.8 ms⁻²
= mass of water
Using conservation of energy, the internal energy produced is same as the gravitational potential energy lost, hence
Internal energy = Gravitational potential energy

It atmosphere is compsosed promarly of hyrogen and helium
Answer:
the knee extensors must exert 15.87 N
Explanation:
Given the data in the question;
mass m = 4.5 kg
radius of gyration k = 23 cm = 0.23 m
angle ∅ = 30°
∝ = 1 rad/s²
distance of 3 cm from the axis of rotation at the knee r = 3 cm = 0.03 m
using the expression;
ζ = I∝
ζ = mk²∝
we substitute
ζ = 4.5 × (0.23)² × 1
ζ = 0.23805 N-m
so
from; ζ = rFsin∅
F = ζ / rsin∅
we substitute
F = 0.23805 / (0.03 × sin( 30 ° )
F = 0.23805 / (0.03 × 0.5)
F F = 0.23805 / 0.015
F = 15.87 N
Therefore, the knee extensors must exert 15.87 N