(adsbygoogle = window.adsbygoogle || []).push({}); A few problems on "MOTION IN ONE DIMENSION"

INTRODUCTION:Here are a problem on "Motion in one-dimension".

THE PROBLEMS:(1) "Car A is just behind Car B.Both are 5m long.The velocity of A is 15 m/s while that of B is 10 m/s. Find the road distnace covered by Car A to cross Car B."

WHAT MY BRAIN SUGGESTED:Let's say Car B moves 'x' distance in time t. So, for Car A to cross Car B, it has to move by a distance of 'x+10' in the same time interval t (since Car A has to move an extra distance of the sum of its own length and that of Car B, so as to cross Car B). So, the equation that stands is x/10 = (x+10)/15. Thus from this equation, x is 20. So, road distance covered by Car A is x+10= (20+10)= 30m.

WHAT MY BOOK SAYS:The answer given in my book is 35m. But i don't know how!

WHAT I WANT TO KNOW:I just wanna know the flaw in my calculation. To me, my method seems allright.But why is the answer not matching?

THE PROBLEMS (Contd.):(2) "A police jeep is chasing with 45 km/h.A thief in another jeep is moving with 155km/h. Police fires a bullet with muzzle velocity 180m/s. Find the velocity with which the bullet strikes the jeep of the thief."How is it possible to find the final velocity without knowing the distance travelled? I mean the problem doesn't give the initial distance between the two jeeps. ***ERROR PROCESSING*** BRAIN CANNOT SUGGEST ANYTHING***INSUFFICIENT DATA FOR MY BRAIN.

WHAT MY BRAIN SUGGESTED:

WHAT MY BOOK SAYS:The solution of this problem is given in my book. It says: "V= v(police) + v(bullet) - v(thief). Putting the values and changing km/h to m/s, the answer given is 150m/s.

WHAT I WANT TO KNOW:How do we get the above formula(the one given in my book)?

CONCLUSION:Hey, I'm really confused. Any help will be appreciated. Thanks a lot.

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# A few problems on MOTION IN ONE DIMENSION

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