Answer:
Explanation:
Given that,
Angular speed of a skater,
The moment of inertia of the skater, I = 0.6 kg-m²
We need to find the angular momentum of the skater. The formula for the angular momentum of the skater is given by :
Substitute all the values,
So, its angular momentum is equal to .
Answer:
Explanation:
There will be loss of potential energy due to loss of height and gain of kinetic energy .
loss of height = R - R cos 14 , R is radius of hemisphere .
R ( 1 - cos 12 )
= 13 ( 1 - .978 )
h = .286 m
loss of potential energy
= mgh
= m x 9.8 x .286
= 2.8 m
gain of kinetic energy
1/2 m v ² = mgh
v² = 2 g h
v² = 2 x 9.8 x 2.8
v = 7.40 m /s
Answer:
the velocity is zero, the acceleration is directed downward, and the force of gravity acting on the ball is directed downward
Explanation:
Is this exercise in kinematics
v = v₀ - g t
where g is the acceleration of the ball, which is created by the attraction of the ball to the Earth.
At the highest point
velocity must be zero.
The acceleration depends on the Earth therefore it is constant at this point and with a downward direction.
The force of the earth on the ball is towards the center of the Earth, that is, down
all other alternatives are wrong
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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