Answer:
From lowest to highest acceleration:
3rd train
2nd train
1st train
Explanation:
The acceleration of an object can be found by using Newton's second law:

where
a is the acceleration
F is the net force on the object
m is the mass of the object
We notice that for equal values of the forces F, the acceleration a is inversely proportional to the mass, m. Therefore, greater mass means lower acceleration, and viceversa.
So, the train with lowest acceleration is the one with largest mass, i.e. the 3rd train consisting of 50 equally loaded freight cars. Then, the 2nd train has larger acceleration, since it consists of 50 empty freight cars (so its mass is smaller). Finally, the 1st train (a single empty car) is the one with largest acceleration, since it is the train with smallest mass.
Answer:

Explanation:
As we know that EMF is induced in a closed conducting loop if the flux linked with the loop is changing with time
So we can say

now we have

here since magnetic field is constant so we have

now we have


now we have


Answer:
Fourth option
Explanation:
They're many different types of energy, from chemical and mechanical to heat and solar energy. But the two most basic types of energy are "kinetic and potential energy" or the fourth option. Kinetic energy is the energy an object has when it is in motion, while potential energy is the energy an object has when it's as rest. These two specific types of energies are the most basic and you can even convert them into many different types of energies, like heat or electrical energy.
Hope this helps.