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.
We know that velocity is equal to the total displacement of an object over time.
Deriving from that equation, we can say that:
Okay, so here it goes:
The bicycle took 25.02 seconds to displace at 58.3 meters.
The gravitational force between a mass and the Earth is the object'sweight. Mass is considered a measure of an object's inertia, and its weight is the force exerted on the object in a gravitational field. On the surface of the Earth, the two forces are related by the acceleration due to gravity: Fg = mg.
Hoped this helped!
Momentum is a product mass and velocity. If a certain object posses a kinetic energy, then it should have a momentum since it is moving which has a velocity. However, if the object is at rest and only has potential energy, then it would not have momentum. So, for the first question the answer would be yes, an object can have energy without having any momentum. For the second question, every object whether it is moving or at rest, possess some energy, potential for an object at rest and kinetic for an object that is moving. Thus, the answer would be no, an object having momentum would always have energy.
The instant it was dropped, the ball had zero speed.
After falling for 1 second, its speed was 9.8 m/s straight down (gravity).
Its AVERAGE speed for that 1 second was (1/2) (0 + 9.8) = 4.9 m/s.
Falling for 1 second at an average speed of 4.9 m/s, is covered <em>4.9 meters</em>.
ANYTHING you drop does that, if air resistance doesn't hold it back.
