Question

27. Supriya is cycling on a circular track. She starts from point A and reaches point B in 20
minutes.
(4 marks)
a) If the speed of her bicycle is 20 km/hr, calculate the distance covered by her and her
displacement as she cycles from point A to B?
b) She cycles from point B back to point A in another 40 minutes. Calculate her average
speed and average velocity in the entire journey from point A to point B and back to
point A.
​​

Answer 1

Answer:

Net acceleration is due to braking and centripetal acceleration

Due to Braking,

a

T

=0.5m/s

2

Speed of the cyclist, v=27km/h=7.5m/s

Radius of the circular turn, r=80m

Centripetal acceleration is given as:

a

c

=

r

V

2

=(7.5

2

)/80=0.70m/s

2

Since the angle between a

c

and a

T

is 900, the resultant acceleration a is given by:

a=(a

c

2

+a

T

2

)

1/2

a=(0.7

2

+0.5

2

)

1/2

=0.86m/s

2

tanθ=

a

T

a

c

where θ is the angle of the resultant with the direction of the velocity.

tanθ=

0.5

0.7

=1.4

θ=tan

−1

(1.4)=54.56

0