Question

Lila is a track and field athlete. She must complete four laps around a circular track. The track itself is a 400 meter track and it took her 6 minutes total to complete.
Which best describes her speed and velocity? (There are 60 seconds in 1 minute.)

A. Her speed is 4.4 m/s, and her velocity is 0 m/s.
B. Her speed is 1.1 m/s, and her velocity is 0 m/s.
C. Her speed is 0 m/s, and her velocity is 2400 m/s.
D. Her speed is 4.4 m/s, and her velocity is 4.4 m/s.

Answer 1

Answer:

A. Her speed is 4.4 m/s, and her velocity is 0 m/s.

Explanation:

Given parameters:

Length of path = 400m

Time taken  = 6min = 360s

Unknown:

Speed and velocity  = ?

Solution:

Velocity is the displacement divide by the time. Displacement takes into the account the distance covered with specific reference to direction. Since the student started and ended the journey on the same spot, the net displacement is 0.

So,

  Since velocity  = $\frac{displacement }{time}$

            Velocity  = 0

Speed is the distance divided by time;

  One lap = 400m,

   four laps  = 400 x 4 = 1600m

Speed  = $\frac{1600}{360 }$  = 4.4m/s