Answer:
t = 300.3 seconds
Explanation:
Given that,
The mass of a freight train, 
Force applied on the tracks, 
Initial speed, u = 0
Final speed, v = 80 km/h = 22.3 m/s
We need to find the time taken by it to increase the speed of the train from rest.
The force acting on it is given by :
F = ma
or

So, the required time is 300.3 seconds.
Answer:
Disambiguation
Explanation:
Fg is an abbreviation used in physics to describe the amount of force exerted by gravity on an object, normally represented in units such as the newton.
#1
As we know that energy of electromagnetic wave is given by

so here we know that penetrating power will directly depends on its energy and energy inversely depends on wavelength
So here we can say correct answer will be
C) The penetrating power decreases as the wavelength increases.
#2
Speed of sound is maximum in solids and minimum in gas
so here as ice melts into water the speed of sound must have to decrease
so correct answer will be
D) The speed of sound would decrease because sound travels faster through solids than liquids.
#3
mechanical waves required medium to travel while non mechanical waves do not require any medium to travel
so here correct answer will be
A) sound
Answer:
» e. Electrons and protons
Explaination :
Electrons are negatively charged and protons are positively charged.
- The neutrons do not have a charge.
Answer:
This is because these metals are used for minting (making) coins.