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Motion in A Plane
Question
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A particle starts with a velocity of 200 cm/s and moves in a straight line with a retardation of 10 cm/s2. Find the time it takes to describe 1500 cm and explain the double answers. 

Answer

Here, we have
Initial velocity, u = 200 cm/s 
Acceleration, a = -10 cm/s2 
Distance travelled, s = 1500 cm 
Time taken, t = ? 
Using the relation, 
        s = ut + 1/2 at2
  1500 = 200 t + 1/2(-10)t2
On solving the equation,we get

t = 10 s or t = 30 s
Here, the value of 10 s corresponds to the time when the particle first arrives at the given location. It then crosses this point and at the end of 20 s, its velocity is just 0. 
The particle then returns and at the end of 10 s more, is again at the given location from the starting point. 

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Some More Questions From Motion in A Plane Chapter

Give three examples of vector quantities.

What are the basic characteristics that a quantity must possess so that it may be a vector quantity?

Is a physical quantity, having a direction, necessarily a vector?

Name a quantity which is both scalar as well as vector.

Which of the followings is/are vector quantities: work, power, acceleration, mass, momentum?

Pick up the odd one from the following: force, linear momentum, mass, impulse.

Pick out the only vector quantities in the following list:
Temperature, pressure, impulse, time, power, total path length, energy, gravitational potential, coefficient of friction and charge.

Pick out the two scalar quantities in the following list:
force, angular momentum, work, current, linear momentum, electric field, average velocity, magnetic moment, reaction as per Newton’s third law, relative velocity.

What are polar vectors?

Give two examples of polar vectors.