Everything Science Grade 10

CHAPTER 20. VECTORS AND SCALARS 20.3

Step 1:Draw a rough sketch of the situation

10 m

2,5 m Wall

Start

Step 2:Decide which method to use to calculate the resultant

We know that the resultant displacement of the ball (~xR) is equal to the

sum of the ball’s separate displacements (~x 1 and~x 2 ):

~xR = ~x 1 +~x 2

Since the motion of the ball is in a straight line (i.e. the ball moves

towards and away from the wall), we can use the method of algebraic

addition just explained.

Step 3:Choose a positive direction

Let’s choose thepositivedirection to be towards the wall. This means

that thenegativedirection is away from the wall.

Step 4:Now define our vectors algebraically

With right positive:

~x 1 = +10,0 m

~x 2 = − 2 ,5 m

Step 5:Add the vectors

Next we simply add the two displacements to give the resultant:

~xR = (+10 m) + (− 2 ,5 m)

= (+7,5) m

Step 6:Quote the resultant

Finally, in this case towards the wall is the positive direction, so:~xR=

7,5 m towards the wall.

Physics: Mechanics 381