uniform acceleration, non-uniform acceleration,Find its acceleration Chapter 8: Motion Science Class 9 solutions are developed for assisting understudies with working on their score and increase knowledge of the subjects. In text Questions of page no 103 is solved by our expert teachers. You can get ncert solutions and notes for class 9 chapter 8 absolutely free. NCERT Solutions for class 9 Science Chapter 8: Motion is very essencial for getting good marks in CBSE Board examinations
In text Questions of page no 103
Q. No 1: When will you say a body is in (i) uniform acceleration? (ii) non-uniform acceleration?
Ans:
(i) A body is said to have uniform acceleration if it travels in a straight path and the velocity of a body increases or decreases by equal amounts in an equal interval of time.
(ii) A body is said to have non-uniform acceleration if it travels in a straight and the velocity of a body increases or decreases in unequal amounts in an equal interval of time.
Q. No 2: A bus decreases its speed from 80 km h-1 to 60 km h-1 in 5 s. Find the acceleration of the bus.
Ans:
Initial velocity of the bus, u = 80 km/h
$ = 80 imes {5 over {18}} = 22.22m/s$
Final velocity of the bus, v = 60 km/h
$ = 60 imes {5 over {18}} = 16.67m/s$
Time take (t) = 5 s
Now acceleration(a)
$eqalign{ & = {{v - u} over t} cr & = {{16.67 - 22.22} over 5} cr & = {{ - 5.55} over 5} cr & = - 1.11m{s^{ - 2}} cr} $
Q. No 3: A train starting from a railway station and moving with uniform acceleration attains a speed 40 km h-1 in 10 minutes. Find its acceleration.
Ans:
Initial velocity of the train (u) = 0 m/s
Final velocity of the train, v = 40 km/h
= 40×5/18=100/9 m/s
Time taken, t = 10 min = 10 × 60 = 600 s
Now, acceleration
$eqalign{ & a = {{v - u} over t} cr & = {{{{100} over 9} - 0} over {600}} cr & = {{100} over {9 imes 600}} cr & = {1 over {54}}m/{s^2} cr} $
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