First example: book, m= 0.75 kg, h=1.5 m, g= 9.8 m/s², it has only potential energy Ep,
Ep=m*g*h=0.75*9.8*1.5=11.025 J
Second example: brick, m=2.5 kg, v=10 m/s, h=4 m, it has potential energy Ep and kinetic energy Ek,
E=Ep+Ek=m*g*h + (1/2)*m*v²=98 J + 125 J= 223 J
Third example: ball, m=0.25 kg, v= 10 m/s, it has only kinetic energy Ek
Ek=(1/2)*m*v²=12.5 J.
Fourth example: stone, m=0.7 kg, h=7 m, it has only potential energy Ep,
Ep=m*g*h=0.7*9.8*7=48.02 J
The order of examples starting with the lowest energy:
1. book, 2. ball, 3. stone, 4. brick 
        
             
        
        
        
Answer:
41.4 g
41.4 cm³
1.08695 g/cm³
Explanation:
 = Density of water = 1 g/cm³
 = Density of water = 1 g/cm³
Mass of water displaced will be the difference of the 

Mass of water displaced is 41.4 g
Density is given by

So, volume of bone is 41.4 cm³
Average density of the bird is given by

The average density is 1.08695 g/cm³
 
        
             
        
        
        
Answer:
speed of car after collision, v2 =16.1 m/s and of the truck, v1 = 4.6 m/s
Explanation:
Given:
mass of truck M = 1370 kg
speed of truck = 12.0 m/s
mass of car m = 593 kg
collision is elastic therefore,
Applying law of momentum conservation we have
momentum before collision = momentum after collision
1370×12 + 0( initially car is at rest) = 1370×v1+ 593×v2               ....(i)
Also for a collision to be elastic,
velocity of approach = velocity of separation
12 -0 = v2-v1                  ....(ii)
using (i) and (ii) we have 
So speed of car after collision, v2 =16.1 m/s and of the truck, v1 = 4.6 m/s
 
        
             
        
        
        
Answer:
Therefore the ratio of diameter of the copper to that of the tungsten is 

Explanation:
Resistance: Resistance is defined to the ratio of voltage to the electricity.
The resistance of a wire is
- directly proportional to its length i.e 
- inversely proportional to its cross section area i.e 
Therefore 

ρ is the resistivity.
The unit of resistance is ohm (Ω).
The resistivity of copper(ρ₁) is 1.68×10⁻⁸ ohm-m
The resistivity of tungsten(ρ₂) is 5.6×10⁻⁸ ohm-m
For copper:


 ......(1)
......(1)
Again for tungsten:

 ........(2)
........(2)
Given that  and
   and    
Dividing the equation (1) and (2)

 [since
   [since  and
   and     ]
]



Therefore the ratio of diameter of the copper to that of the tungsten is 

 
        
             
        
        
        
Answer:
If a Gaussian surface is completely inside an electrostatic conductor, the electric field must always be zero at all points on that surface.
Explanation:
Option A is incorrect because, given this case, it is easier to calculate the field.
Option B is incorrect because, in a situation where the surface is placed inside a uniform field, option B is violated
Option C is also incorrect because it is possible to be a field from outside charges, but there will be an absence of net flux through the surface from these.
Hence, option D is the correct answer. "If a Gaussian surface is completely inside an electrostatic conductor, the electric field must always be zero at all points on that surface."