Answer: 909 m/s
Explanation:
Given
Mass of the bullet, m1 = 0.05 kg
Mass of the wooden block, m2 = 5 kg
Final velocities of the block and bullet, v = 9 m/s
Initial velocity of the bullet v1 = ? m/s
From the question, we would notice that there is just an object (i.e the bullet) moving before the collision. Also, even after the collision between the bullet and wood, the bullet and the wood would move as one object. Thus, we would use the conservation of momentum to solve
m1v1 = (m1 + m2) v, on substituting, we have
0.05 * v1 = (0.05 + 5) * 9
0.05 * v1 = 5.05 * 9
0.05 * v1 = 45.45
v1 = 45.45 / 0.05
v1 = 909 m/s
Thus, the original velocity of the bullet was 909 m/s
Technically? It's not wrong. A star is a ball of gas that is held together by it's own gravity of which it constantly struggles against. Gravity constantly works to try and make the star collapse. However, stars are extremely hot at their cores which help the star push against it's own gravity creating a sort of equilibrium. So long as the star continues to push against gravity, it will not collapse, however eventually a star will lose its energy and eventually collapse into a black hole.
Explanation:
Image distance, v = -17 cm (-ve for virtual image)
Radius of curvature of concave mirror, R = 39 cm
Focal length, f = -19.5 cm (-ve for a concave mirror)
(a) Using mirror's formula as :
u = 132.6 cm
So, the object is placed 132.6 cm in front of the mirror.
(b) Magnification of the mirror, 
m = -0.128
Hence, this is the required solution.
