Q.no.5

Asked by rajsolankiveer | 11th Jun, 2020, 05:08: PM

Expert Answer:

Step 1 : Fnding the acceleration of the train when it is at the distance of 2 km from the pole.
 
begin mathsize 12px style straight v squared space equals space straight u squared plus 2 as
end style
final velocity 'v' is 0 because it is assumed that the train is supposed to stop when it reaches the pole.
initial velocity = 20 km/hr ...(given)
s = 2 km, the distance of the train from the pole.
 
begin mathsize 12px style straight v squared space equals space straight u squared plus 2 as
0 equals space 20 squared plus 2 straight a left parenthesis 2 right parenthesis
straight a equals fraction numerator negative 400 space over denominator 4 end fraction
straight a equals space minus 100 space km divided by hr squared
end style
 
Step 2: Finding the time in which the train travelled 2kms to the pole.
 
begin mathsize 12px style straight v space equals space straight u plus at
0 equals 20 space plus space left parenthesis negative 100 right parenthesis straight t
straight t equals fraction numerator negative 20 over denominator negative 100 end fraction equals 1 fifth space hr end style
 
Step 3: Finding the distance that the bird covers in the above period of time.
 
distance = speed (of bird) x time (above calculated)
begin mathsize 12px style distance space equals space 60 space straight x space 1 fifth
distance space equals space 12 space km end style

Answered by Shiwani Sawant | 11th Jun, 2020, 07:28: PM