Question

The equation of motion of a cyclist has the form: x = 40 - 8t. Determine the direction and speed at which the cyclist is moving: *

Answer 1

To be given in question

x=40 - 8t$\longrightarrow (1)$

To be asked in question

Direction and speed =?

equation (1) take differenciate with respect t

$\frac{dx}{dt}=-8 \longrightarrow (2)$

Speed always positive

$\ |\frac{dx}{dt}|=|-8|$

$Speed (v)=8 meter/sec$

Speed = 8 meter/sec

Speed direction:-

$\frac{dx}{dt}=-8$

velocity is negetive mean speed direction is negative x-axis

speed direction is negative (-x) direction.