Answer:
20 cm
Explanation:
Given that a ball is released from a vertical height of 20 cm. It rolls down a "perfectly frictionless" ramp and up a similar ramp. What vertical height on the second ramp will the ball reach before it starts to roll back down?
Since it is perfectly frictionless, the Kinetic energy in which the ball is rolling will be equal to the potential energy at the edge of the ramp.
Therefore, the ball will reach 20 cm before it starts to roll back down.
Answer:........... .. .....
Explanation:
The weight of the car is equal to,
...........(1)
Where
m is the mass of car
g is the acceleration due to gravity
The normal or vertical component of the force is, 
or
.............(2)
The horizontal component of the force is, 
Taking ratio of equation (1) and (2) as :



or

Hence, this is the required solution.
Similarities:
The halogens like noble gases are gaseous im nature. Example,
Chlorine, bromine are halogens and argon , xenon are noble gases.
Both are non-metals.
Differences: Halogens are very reactive because their octet needs only one electron tk complete. But, the nobles gases are quite stable and unreactive because the have complete octets.
The earth is so round that we can run around it in five million days