Ah hah ! Very nice problem.
-- Since the mass is 1/2 of the Earth's mass, the gravitational forces between him
and the new planet would be 1/2 of what they are on Earth.
-- Since the distance between him and the center of the new planet is 1/2 of the
distance between him and the Earth's center, the gravitational forces between him
and the new planet would be (2)² = 4 times what they are on Earth.
-- These conditions combine to make his weight (1/2) x (4) = 2 times his earth weight.
-- He weighs 1,000 N (about 224.8 pounds) on the new planet.
(Maybe that's why they selected an astronaut for this mission who only weighs
about 112.5 pounds on Earth.)
Well, Velocity is the speed of something in a given direction, and speed is the rate at which someone or something is able to more or operate. They both invlove speed, so this is a hard one, but I wold say either B or D
The speed of bullet =
850 m/s
Distance given = 1 km = 1000m
S = D/t
t • S = D/t • t
St = D
St/S = D/S
t = D/S
t = 1000m/850m/s
t = 1.176 s
It will take the bullet 1.176 or about 1.18 seconds to go 1 km.
The correct choice is
D. 22 Hz and 42 Hz.
In fact, the beat frequency is given by the difference between the frequencies of the two waves:
In this problem, the beat frequency is 
, therefore the only pair of frequencies that gives a difference equal to 20 Hz is
D. 22 Hz and 42 Hz.
I believe that it is the first one just a guess tho. So don't trust me, just in case
