Everything Science Grade 10

21.7 CHAPTER 21. MOTION IN ONE DIMENSION

• its acceleration


• its final velocity


• at what time the motorcycle had covered half the total distance


• what distance the motorcycle had covered in half the total time.

SOLUTION

Step 1:Identify what information is given and what is asked for

We are given:

~vi = 0m·s−^1 (because the object starts from rest.)

∆~x = 64m

t = 4s

~a =?

~vf =?

t = ?at half the distance∆~x= 32 m.

∆~x = ?at half the timet= 2 s.

All quantities are in SI units.

Step 2:Acceleration: Find a suitable equation to calculate the acceleration

We can use Equations 21.3

∆~x=~vit+^12 ~at^2

Step 3:Substitute the values and calculate the acceleration

∆~x = ~vit+^12 ~at^2

64 m = (0 m·s−^1 × 4 s) +^12 ~a×(4s)^2

64 m = (8s^2 )~a

~a = 8 m·s−^2 East

Step 4:Final velocity: Find a suitable equation to calculate the final velocity

We can use Equation 21.1 - remember we now also know the acceler-

ation of the object.

~vf=~vi+~at

428 Physics: Mechanics