Answer:
To achieve the velocity of 40 m/sec height will become 4 times
Explanation:
We have given initially truck is at rest and attains a speed of 20 m/sec
Let the mass of the truck is m
At the top of the hill potential energy is mgh and kinetic energy is 
So total energy at the top of the hill 
At the bottom of the hill kinetic energy is equal to
and potential energy will be 0
So total energy at the bottom of the hill is equal to 
Form energy conservation 
, for v = 20 m/sec

Squaring both side

h = 20.408 m
Now if velocity is 0 m/sec


h = 81.63 m
So we can see that to achieve the velocity of 40 m/sec height will become 4 times
Complete Question
The complete question is shown on the first uploaded image
Answer:
A

B

C
The correct option is B
Explanation:
From the question we are told that
The refractive index of water is 
The refractive index of ethanol is 
Generally the threshold velocity for creating Cherenkov light from a charged particle as it travels through water is mathematically evaluated as

Where c is the speed of light with value 


Generally the threshold velocity for creating Cherenkov light from a charged particle as it travels through water is mathematically evaluated as

=> 
=> 
Answer:
3kg
Explanation:
impulse = MV
then
m1v1=m2v2
when the values are subtitude
then
m2=1.2*25/10
m2=<em>3</em><em>0</em><em>k</em><em>g</em><em>/</em><em>/</em>