A friend throws a baseball horizontally. He releases it at a height of 2.0 m and it lands 21 m from his front foot, which is dir
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Answer:
Explanation:
This is a recoil problem, which is just another application of the Law of Momentum Conservation. The equation for us is:
which, in words, is
The momentum of the astronaut plus the momentum of the piece of equipment before the equipment is thrown has to be equal to the momentum of all that same stuff after the equipment is thrown. Filling in:
Obviously, on the left side of the equation, nothing is moving so the whole left side equals 0. Doing the math on the right and paying specific attention to the sig fig's here (notice, I added a 0 after the 4 in the velocity value so our sig fig's are 2 instead of just 1. 1 is useless in most applications).
0 = 90.0v - 2.0 and
2.0 = 90.0v so
v = .022 m/s This is the rate at which he is moving TOWARDS the ship (negative was moving away from the ship, as indicated by the - in the problem). Now we can use the d = rt equation to find out how long this process will take him if he wants to reach his ship before he dies.
12 = .022t and
t = 550 seconds, which is the same thing as 9.2 minutes
Answer:
The number of photons per second are .
Explanation:
Given that,
Wavelength = 650 nm
Power = 45 W
Distance R= 17 m
Diameter = 5.0 mm
We need to calculate the number of photon per second emitted by light bulb
Using formula of energy
The power is
Put the value of E
Put the value into the formula
We need to calculate the surface area
Using formula of area
We need to calculate the number of photons entering into eye
Hence, The number of photons per second are .