Answer:

Given:
Initial velocity (u) = 30 m/s
Final speed (v) = 0 m/s
Acceleration (a) = - 1.5 m/,s²
To Find:
Time in which train will come to rest (t).
Explanation:

So,
Time in which train will come to rest = 20 seconds
Answer:
1 second later the vehicle's velocity will be:

5 seconds later the vehicle's velocity will be:

Explanation:
Recall the formula for the velocity of an object under constant accelerated motion (with acceleration "
"):

Therefore, in this case
and 
so we can estimate the velocity of the vehicle at different times just by replacing the requested "t" in the expression:

Answer:
Propels in the opposite direction
Explanation:
Explanation:
Given that,
The mean kinetic energy of the emitted electron, 
(a) The relation between the kinetic energy and the De Broglie wavelength is given by :



(b) According to Bragg's law,

n = 1
For nickel, 



As the angle made is very small, so such an electron is not useful in a Davisson-Germer type scattering experiment.