Everything Science Grade 12

6.5 CHAPTER 6. MOTIONIN TWO DIMENSIONS

Since xeis not equal to zero we can divide throughout by xe.

2

10 s

=

1

15 s

+

1

t

Re-write:

2

10 s

−

1

15 s

=

1

t

Multiply by t:

t

�

2

10 s

−

1

15 s

�

= 1

Solve for t:

t =

1

2

10s−

1

15s

=

15

2

s

Step 4 : Write the final answer

The man will take 15/2= 7,5 s

Exercise 6 - 4

1. A woman walks north at 3 km·hr−^1 on a boat that is movingeast at 4 km·hr−^1.
   This situation is illustrated in the diagram below.

(a) How fast is the woman moving according toher friend who is also on the

boat?

(b) What is the woman’s velocity according toan observer watching from the

river bank?

� 3km·hr

− 1

4km·hr−^1

N

2. A boy is standing inside a train that is moving at 10 m·s−^1 to the left. The boy
   throws a ball in the air with a velocity of 4 m·s−^1. What is the resultant velocity
   of the ball

(a) according to the boy?