What is the angle of incidence in air of a light ray whose angle of refraction in glass is half the angle of incidence? Show pro
1 answer:
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1) 5.5 N
When the ball is at the bottom of the circle, the equation of the forces is the following:
where
T is the tension in the string, which points upward
mg is the weight of the string, which points downward, with
m = 0.158 kg being the mass of the ball
g = 9.8 m/s^2 being the acceleration due to gravity
is the centripetal force, which points upward, with
v = 5.22 m/s being the speed of the ball
R = 1.1 m being the radius of the circular trajectory
Substituting numbers and re-arranging the formula, we find T:
2) 3.9 N
When the ball is at the side of the circle, the only force acting along the centripetal direction is the tension in the string, therefore the equation of the forces becomes:
And by substituting the numerical values, we find
3) 2.3 N
When the ball is at the top of the circle, both the tension and the weight of the ball point downward, in the same direction of the centripetal force. Therefore, the equation of the force is
And substituting the numerical values and re-arranging it, we find
4) 3.3 m/s
The minimum velocity for the ball to keep the circular motion occurs when the centripetal force is equal to the weight of the ball, and the tension in the string is zero; therefore:
and re-arranging the equation, we find
Answer:
a) 567J
b) 283.5J
c)850.5J
Explanation:
The expression for the translational kinetic energy is,
Substitute,
14kg for m
9m/s for v
The translational kinetic energy of the center of mass is 567J
(B)
The expression for the rotational kinetic energy is,
The expression for the moment of inertia of the cylinder is,
The expression for angular velocity is,
substitute
1/2mr² for I
and vr for w
in equation for rotational kinetic energy as follows:
The rotational kinetic energy of the center of mass is 283.5J
(c)
The expression for the total energy is,
substitute 567J for E(r) and 283.5J for E(R)
The total energy of the cylinder is 850.5J