Question

A cyclist completes 2 revolutions of a circular path of diameter 20m in half minute. calculate the speed of the cyclist

Answer 1

Answer:

1.3m/s

Step-by-step explanation:

Speed= s/t= 40/30= 4/3=1.3m/s

Answer 2

Answer:

Speed = 3.22m/s

Step-by-step explanation:

Given:

Diameter = 20m

Radius = 20/2 = 10m in 1/2 minute

To find:

Speed of cyclist = ?

Formula Used :

• Circumference = 2πr

• $speed = \dfrac{distance}{time}$

Procedure:

$\: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \implies \sf \: circmufrence \: = \: 2 \times \dfrac{22}{7} \times 10$

$\: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \implies \sf \: circmufrence \: = \dfrac{440}{7} m$

$\: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \implies \sf \: circmufrence \: =62.857m$

$\: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \implies \sf \: circmufrence \: on \: completing \: two \: revolution \: = \: 62.857m \times 2$

$\: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \implies \sf \: circmufrence \: on \: completing \: two \: revolution \: = \:125.714m$

½ minute = 30 sec (½ × 60sec)

We know ,

$\: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \implies \sf \: speed \: = \: \dfrac{distance}{time}$

$\: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \implies \sf \: speed \: = \: \dfrac{125.714m}{30s}$

$\: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \implies \sf \: speed \: = \: \: 3.22 \: m/s$

Points to remember:

• Speed is the rate of change of distance.

• Average Speed is the total distance travelled, divided by total time taken.

• Speed is a scalar quantity.

• Velocity is a vector quantity.