Mv + mv = 2mv providing each momentum is in the same direction.
1/2 mv^2 + 1/2 mv^2 = mv^2
Explanation:
It is given that,
Frequency of the laser light, 
Time,
(a) Let
is the wavelength of this light. It can be calculated as :



or

(b) Let n is the number of the wavelengths in one pulse. It can be calculated as :


n = 13440
Hence, this is the required solution.
Answer: The height above the release point is 2.96 meters.
Explanation:
The acceleration of the ball is the gravitational acceleration in the y axis.
A = (0, -9.8m/s^)
For the velocity we can integrate over time and get:
V(t) = (9.20m/s*cos(69°), -9.8m/s^2*t + 9.20m/s^2*sin(69°))
for the position we can integrate it again over time, but this time we do not have any integration constant because the initial position of the ball will be (0,0)
P(t) = (9.20*cos(69°)*t, -4.9m/s^2*t^2 + 9.20m/s^2*sin(69°)*t)
now, the time at wich the horizontal displacement is 4.22 m will be:
4.22m = 9.20*cos(69°)*t
t = (4.22/ 9.20*cos(69°)) = 1.28s
Now we evaluate the y-position in this time:
h = -4.9m/s^2*(1.28s)^2 + 9.20m/s^2*sin(69°)*1.28s = 2.96m
The height above the release point is 2.96 meters.
Answer:
V (initial vertical velocity) = 45.4 sin 31.2 = 23.52 m/s
1/2 m V^2 = m g h conservation of energy
h = V^2 / (2 g) = 23.52^2 / 19.6 = 28.2 m max height
Check:
t = 28.2 / 9.8 = 2.88 sec time to reach max height
h = 23.52 * 2.88 - 1/2 g 2.88^2 = 27.1 m