Answer:

Explanation:
By Snell's law we know at the left surface




now we have


now on the other surface we know that
angle of incidence = 

so again we have

so we have


also we know that


By solving above equation we have

Answer:
The answer is: To accelerate an object <u>the force applied to the object</u> has to increase.
Explanation:
the acceleration of an object <u>increases with increased force</u> and <u>decreases with increased mass.</u>
Answer:
<h2>Force due to biceps is given as</h2><h2>

</h2>
Explanation:
For balancing the force we know that
Torque due to weight hold on his hand = torque due to force applied by biceps
So here we will have

so we have


Answer: T= 715 N
Explanation:
The only external force (neglecting gravity) acting on the swinging mass, is the centripetal force, which. in this case, is represented by the tension in the string, so we can say:
T = mv² / r
At the moment that the mass be released, it wil continue moving in a straight line at the same tangential speed that it had just an instant before, which is the same speed included in the centripetal force expression.
So the kinetic energy will be the following:
K = 1/2 m v² = 15. 0 J
Solving for v², and replacing in the expression for T:
T = 1.9 Kg (3.97)² m²/s² / 0.042 m = 715 N