Relative motion means a motion relative to a reference point. We can also say, relative motion means motion referred or observed from a reference point.
For example, Alex is in a train and Ace is at the station, when the train starts moving, for Ace it is moving at a speed of 10 m/s, but for Alex it is moving at 0 m/s, or we can say that it is at rest for Alex, but in motion for Ace. This is relative motion.
 
        
                    
             
        
        
        
Answer:
d. decreases
Explanation:
The law of conservation of momentum tells us that the sum of momenta before the collision is equal to the sum of momenta after the collision. The bag has no momentum as it falls onto the boat because its velocity is zero in the horizontal direction. But after it hits the boat, it's momentum increases while the momentum of the system remains the same. That means a component of the system must decrease somewhere else. And that component is the velocity, not the mass, of the boat.
 
        
             
        
        
        
Answer:
The wire now has less (the half resistance) than before.
Explanation:
The resistance in a wire is calculated as:
 

 
Were:
R is resistance
 is the resistance coefficient
 is the resistance coefficient
l is the length of the material
s is the area of the transversal wire, in the case of wire will be circular area ( ).
).
 
So if the lenght and radius are doubled, the equation goes as follows:
 

 
So finally because the circular area is a square function, the resulting equation is half of the one before.
 
        
             
        
        
        
Answer:

Explanation:
When the rock is immersed in unknown liquid the forces that act on it are shown as under
1) Tension T by the string
2) Weight W of the rock
3) Force of buoyancy due to displaced liquid B
For equilibrium we have 
 =
=
When the rock is suspended in air for equilibrium we have

When the rock is suspended in water for equilibrium we have
 +
 +  =
=
Using the given values of tension and solving α,β,γ simultaneously for  we get
 we get

Solving for density of liquid we get

