A bus is moving with a velocity of 72km/hr. on seeing the red signal of traffic at 27m ahead on the road, the driver applied brakes and the bus stopped at a distance of 25m. calculate the time taken by the car to come at rest plz help me

Since there is negative acceleration, a= -2m/s^2 . As brakes are applied, it's final velocity (v) becomes 0m/s and it's initial velocity (u) will be 20m/s .

So to find the time for which my Nano will stop we make use of one of the kinematical equation.

v=u+at  

0=20+(−2)t  

−20=−2t  

t=10seconds.  

So my Nano will take 10 seconds to stop.

Now to calculate the distance for which my Nano will stop is given by;

v2=u2+2ax  

(0)2=(20)2+2(−2)x  

0=400−4x  

−400=−4x  

x=100metres.  

So after applying brakes my Nano will stop after a distance of 100m.

Explanation:

answer: at 24 february, 2014 the population gets twice of its initial population.

explanation:

since we have given that

the population for alpha city, t years after january 1, 2004 is given as

first we find out the initial population, i.e. t=0,

so, our quadratic equation becomes,

according to question, we have said that if the population has twice its initial population, then it becomes

so, time taken to reach this above mentioned population is given by

now, we know that time can't be negative so, we take t=9.149 years.

hence, at 24 february, 2014 the population gets twice of its initial population.