To calculate the ideal mechanical advantage of a lever divide the input arm by the output arm.
Mechanical advantage is the amount by which a machine can multiply an input force, calculated by dividing output Force in newtons by input force in newtons, while the ideal mechanical advantage is the mechanical advantage of a machine that has no friction, calculated by dividing the input distance by the output distance.
Answer:
a.proton, proton
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Answer:

Explanation:
As we know that train is initially moving with the speed

now we know that

now the final speed of the train when it crossed the crossing


now we can use kinematics here



Now the time to cross that junction is given as



Answer:
4. Electrons move from higher energy states to lower energy states.
Explanation:
When electrons fall from a higher (excited) energy state to a lower energy state, it loses/gives out energy.
This energy is given out by the emission of photons (quanta of light) by the electron.