Answer:
Gravity is the force of attraction between two objects; it is dependent upon the mass of the objects and the distance between the objects.
Explanation:
Gravity is defined as the force of attraction between two objects. It depends on the masses of objects and the distance between them. The gravitational force between two bodies is given by the universal law of gravitation. According to this law, the force of gravity is :
Where
G is the universal gravitational constant
m₁ and m₂ are masses of two bodies
d is the distance between two bodies
Hence, the correct statement that describes gravity is (b)
Answer: Rock require larger drag force and to achieve it rock need to move at a very high terminal velocity.
Explanation: Terminal velocity is defined as the final velocity attained by an object falling under the gravity. At this moment weight is balanced by the air resistance or drag force and body falls with zero acceleration i.e. with a constant velocity.
Case 1: Terminal velocity of a piece of tissue paper.
The weight of tissue paper is very less and it experiences an air resistance while falling downward under the effect of gravity.
Downward gravitational force, F = mg
Upward air resistance or friction or drag force will be 
So, paper will attain terminal velocity when mg =
Case 2: Rock is very heavy and require larger air resistance to balance the weight of rock relative to the tissue paper case.
Downward force on rock, F = Mg
Drag force = 
Rock will attain terminal velocity when Mg =
Mg > mg
so, >
And rock require larger drag force and to achieve it rock need to move at a very high terminal velocity.
<h2>Answer: True
</h2>
The <u>Doppler effect</u> refers to the change in a wave perceived frequency when the emitter of the waves, and the receiver (or observer in the case of light) move relative to each other.
In other words, it is the variation of the frequency of a wave due to the relative movement of the source of the wave with respect to its receiver.
It should be noted that this effect bears its name in honor of the Austrian physicist <u>Christian Andreas Doppler</u>, who in 1842 proposed the existence of this effect for the case of light in the stars. Another important aspect is that the effect occurs in all waves (including light and sound). However, it is more noticeable to humans with sound waves.
Answer:
The distance is 
Explanation:
From the question we are told that
The wavelength of the light is 
The distance between the slit is 
The between the first and second dark fringes is 
Generally fringe width is mathematically represented as
Where D is the distance of the slit to the screen
Hence
substituting values
Answer:
Explanation:
Let assume begins movement at zero point, that is, height is equal to zero. The block has an initial linear kinetic energy and no gravitational potential energy and end with no linear kinetic energy, some gravitational potential energy and work losses due to slide friction. In mathematical terms, this system can be model as follows:
Where 
are linear kinetic energy, gravitational potential energy and work, respectively.
