Question

A boy walks 10 m due west and 10m due south.What is the displacement.[2]a girl walks 12m northwards,5m eastwards and 7m southwards.Calculate her total displacement[3]a man walks 5km south and 3km in the direction 60 degree west of south.Calculate his distance from starting point.

Answer 1

these all just use the Pythagorean Theorem, or the distance formula, which is the same.

Just figure out the final location, and then use the formula.

For #1,

(0,0) -> (-10,0) -> (-10,-10)
distance is √(10^2+10^2) = 14.1

Answer 2

Using Pythagoras theorem the answer is 14.1 for question 1

Answer 3

2. Disp. = 12i + 5 - 7i = 5 + 5i = 7.07m[45o].

3. All angles are measured CW from +y-axis.
Disp. = 5[180o] + 3[240o].
X = 5*sin180 + 3*sin240 = -2.60 km.
Y = 5*Cos180 + 3*Cos240 = -6.5 km.
Disp. = -2.60 + (-6.5)I = 7.0[22o] W. of S. = 7.0km[202o] CW.