I believe the answer is A, temperature and number of particles are constant. Correct me if i'm wrong :)
Answer:
f = 15 N
Explanation:
It is given that, when you push with a horizontal 15-N force on a book that slides at constant velocity, a frictional force also acts on it. Frictional force is an opposing force. The magnitude of applied force and frictional forces are same. So, the force of friction on the book is equal to 15 N.
Answer:
The critical angle for light is 41.81 degrees.
Explanation:
We have, light is propagating from a material with index of refraction of 1.50 to a material with index of refraction of 1. It is required to find the critical angle for light. It is angle for which the angle of refraction is equal to 90 degrees. It is given by :

So, the critical angle for light is 41.81 degrees.
C. one complete spin on its axis because the rotation is referring to the planet's period of rotation. D is called a revolution. B determines the seasons on the planets. A is called an ellipse.
Answer:
4.44 i + 11.11 j , 11.96 m/s
Explanation:
m1 = 0.2 kg, v1 = 10 m/s along X axis, v1 = 10 i
m2 = 0.25 kg, v2 = 20 m/s along north, v2 = 20 j
After collision they stick together and let they move with velocity v.
Use the conservation of momentum
m1 x v1 + m2 x v2 = (m1 + m2) x v
0.2 x (10 i) + 0.25 x (20 j) = (0.2 + 0.25) x v
2i + 5j = 0.45 v
v = 4.44 i + 11.11 j
magnitude of velocity =
= 11.96 m/s
Thus, the velocity of 0.250 kg hockey puck is 4.44 i + 11.11 j metre per second and the magnitude of velocity is 11.96 m/s.