The kinetic energy of a book on a shelf is equal to the work done to lift the book to the shelf is false. The kinetic energy on the shelf is zero because it is not in action.
Answer:
(a). The angle of refraction is 19.26°.
(b). That is proved that the rays in air on either side of the glass are parallel to each other
Explanation:
Given that,
Angle of incidence = 30.0°
Index of reflection of glass = 1.52
(a). We need to calculate the angle of refraction for the ray inside the glass
Using snell's law


Put the value into the formula



(b). We know that,
The incident ray and emerging ray is equal then the ray will be parallel.
We need to prove that the rays in air on either side of the glass are parallel to each other
Using formula for emerging ray


Put the value into the formula



So, 
This is proved.
Hence, (a). The angle of refraction is 19.26°.
(b). That is proved that the rays in air on either side of the glass are parallel to each other
Answer:
False
Explanation:
The 3 important steps to a perfect forehand in tennis are Preparation,Backswing and Swing and contact.
Answer:
0.78 m
Explanation:
By the conservation of energy, the energy that they gain from potential energy, must be equal to the kinetic energy. So, for Adolf:
Ep = Ek
ma*g*ha = ma*va²/2
Where ma is the mass of Adolf, g is the gravity acceleration (10 m/s²), ha is the height that he reached, and va is the velocity. So:
100*10*0.51 = 100*va²/2
50va² = 510
va² = 10.2
va = √10.2
va = 3.20 m/s
Before the push, both of them are in rest, so the momentum must be 0. The system is conservative, so the momentum after the push must be equal to the momentum before the push:
ma*va + me*ve = 0, where me and ve are the mass and velocity of Ed. So:
100*3.20 + 81ve = 0
81ve = 320
ve = 3.95 m/s
By the conservation of energy for Ed:
me*g*he = me*ve²/2
81*10*he = 81*(3.95)²/2
810he = 631.90
he = 0.78 m