Laws of Motion 4 Question 2

2. A particle is moving along a circular path with a constant speed of 10ms1. What is the magnitude of the change in velocity of the particle, when it moves through an angle of 60 around the centre of the circle?

(2019 Main, 11 Jan I)

(a) 102m/s

(b) 10m/s

(c) 103m/s

(d) Zero

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Answer:

Correct Answer: 2. (b)

Solution:

  1. Let v1 be the velocity of the particle moving along the circular path initially, v1 and v2 be the velocity when it moves through an angle of 60 as shown below.

From the figure,

Δv=v2v1|Δv|=2vsinθ2=2vsin30[|v1|=|v2|]=2v×12=v( Given, v=10m/s)|Δv|=10m/s

Alternate method

Δv=v2v1=v2+(v1)

|Δv|2=v12+v22+2v1v2cos120

=v2+v2+2v×v×12

|Δv|=v=10m/s.



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