Question

boy A is standing at a point 3 m west and 4 m south to boy B. Assume the east and the north towards the positive x and y axis of coordinate system. boy a starts moving along a vector a =1.5 i +2 j with a constant speed of 2m/s for 5 seconds and stops. now how far is the boy A from the boy B ?

Answer 1

Answer:

15 m

Explanation:

boy A is standing at a point 3 m west and 4 m south to boy B. Assume the east and the north towards the positive x and y axis of coordinate system. boy a starts moving along a vector a =1.5 i +2 j with a constant speed of 2m/s for 5 seconds and stops. now how far is the boy A from the boy B ?

let say boy B is standing at origin (0,0)

then boy A is standing (-3 , -4)

boy A move 1.5i + 2 j

distance moved = 2 × 5 = 10m

1.5i + 2j = root (1.5^2 + 2^2) = 2.5

distance moved toward i = east =(1.5)/(2.5) × 10 = 6 m

distance moved toward j = north = (2/2.5) × 10 = 8m

BoyA = ( 6, 8)

Boy B = (-3 , -4)

distance between boy A& B = root ( (6-(-3))^2 + (8 -(-4))^2)

= root ( 9^2 + 12^2)

= root ( 81 + 144)

= root 225

= 15 m