when the ball hits the floor and bounces back the momentum of the ball changes.
the rate of change of momentum is the force exerted by the floor on it.
the equation for the force exerted is
f = rate of change of momentum

v is the final velocity which is - 3.85 m/s
u is initial velocity - 4.23 m/s
m = 0.622 kg
time is the impact time of the ball in contact with the floor - 0.0266 s
substituting the values

since the ball is going down, we take that as negative and ball going upwards as positive.
f = 189 N
the force exerted from the floor is 189 N
Answer:b) atoms
Explanation:which are in turn made up of protons, neutrons and electrons
21N
Explanation:
Given parameters:
Mass of wagon = 14kg
Acceleration = 1.5m/s²
Unknown:
Net force on wagon = ?
Solution:
Force is a pull or push on a body that causes a body to change its state. It is expressed as:
Force = mass x acceleration
Force on wagon = 14 x 1.5 = 21N
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Let us consider two bodies having masses m and m' respectively.
Let they are separated by a distance of r from each other.
As per the Newtons law of gravitation ,the gravitational force between two bodies is given as -
where G is the gravitational force constant.
From the above we see that F ∝ mm' and 
Let the orbital radius of planet A is
= r and mass of planet is
.
Let the mass of central star is m .
Hence the gravitational force for planet A is 
For planet B the orbital radius
and mass
Hence the gravitational force 
![f_{2} =G\frac{m*3m_{1} }{[2r_{1}] ^{2} }](https://tex.z-dn.net/?f=f_%7B2%7D%20%3DG%5Cfrac%7Bm%2A3m_%7B1%7D%20%7D%7B%5B2r_%7B1%7D%5D%20%5E%7B2%7D%20%7D)

Hence the ratio is 
[ ans]
Answer:
Explained below
Explanation:
1) Liquid in glass thermometer: This type of thermometer is used primarily to measure the temperatures from inspection of changes in volume of liquid.
Thermometry substance is mercury or alcohol
2) Gas thermometer: This type is used to measure temperature as a result of changes in gas pressure or volume.
Thermometry substance is Gas.
3) Resistance thermometer: This type is used to measure temperature due to changes in electric resistance.
Thermometry substance is Resistance wire.
4) Thermocouple thermometer: This type is used to measure the temperature due to changes in electrical potential difference occurring between two metal junctions.
Thermometry substance is two wires that are dissimilar.
5) Bimetallic thermometer: This is a type of thermometer that measures temperature by converting temperature into mechanical displacement by making use of Bimetallic strip.
Thermometry substance is two metals that are dissimilar.