Answer:
548.5 Hz
Explanation:
We are given that
Frequency of source=500 Hz
Speed of train=30m/s
Speed of sound in air=339m/s
We have to find the frequency of the bell to an observer riding the train.
The apparent frequency for the listener
Where 
Frequency of source
=Speed of sound
=Speed of source
Using the formula
The apparent frequency of the bell to an observer riding the train=
Hence, the apparent frequency of the bell to an observer riding the train=548.5 Hz
Answer:
The correct option is;
D) The force exerted on the astronaut by Earth is equal to the force exerted on Earth by the astronaut
Explanation:
According to Newton's third law of motion, in nature, for every action, there is an equal and opposite reaction, such that if a first object exerts a certain amount of force on a second object, the second object will exert a force of equal magnitude and opposite direction to that exerted by the first object
Therefore, the gravitational force exerted by Earth on the astronaut, is equal to the force exerted by the astronaut on Earth.
ans: B
Kinetic energy = 
= 
= 50J
ps. the height will only affect its potential energy, not kinetic.
Answer:
The frequency of the wave is 5 x 10⁹ Hz
Explanation:
Given;
wavelength of the radio wave, λ = 6.0 × 10⁻²m
radio wave is an example of electromagnetic wave, and electromagnetic waves travel with speed of light, which is equal to 3 x 10⁸ m/s².
Applying wave equation;
V = F λ
where;
V is the speed of the wave
F is the frequency of the wave
λ is the wavelength
Make F the subject of the formula
F = V / λ
F = (3 x 10⁸) / (6.0 × 10⁻²)
F = 5 x 10⁹ Hz
Therefore, the frequency of the wave is 5 x 10⁹ Hz
Your answer would be D.
If an object has mass, it has gravity, and the more mass it has, the stronger its gravity. During the formation of planets, essentially, various matter and elements pulled and fused together (because of the gravity), forming planetesimals.
