KVPY SA Exam 2015 Question Paper

Question : 18 of 80

Marks: +1, -0

An object at rest at the origin begins to move in the +x direction with a uniform acceleration of 1 m/

s^2

for 4 s and then it continues moving with a uniform velocity of 4 m/s in the same direction. The x - t graph for object’s motion will be

Solution:

x=1/2at^2

parabolic for 0 to 4 sec
[at t = 4 sec x

= 12 × (1) (4)^2 = 8

m]
then after (v = 4 m/s)
v = 4

{dx}/{dt}=4

∫↖{x}↙{8}dx=∫↖{t}↙{4}4dt

x – 8 = 4 (t - 4)

x = 4t- 8

(st. line)

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