Kinematics

Question 1

Difference between vector and scalar measurements

Answer 1

Vector has direction and magnitude whilst scalar has magnitude

Question 2

Define speed
Define acceleration

Answer 2

Speed is the time rate at which an object is moving along its pathway.
distance/time
The rate at which an object changes its velocity is called its acceleration.
𝒂=(𝒗−𝒖)/𝒕
a = acceleration (ms-2)
v = final velocity (ms-1)
u = initial velocity (ms-1)
t = time (s)

Question 3

Instantaneous velocity vs average velocity

Answer 3

Instantaneous velocity is the velocity - speed and direction of travel at a specific time
Average velocity is the change in displacement per second over a specified time interval
𝑣_𝑎𝑣𝑒𝑟𝑎𝑔𝑒=((𝑣+𝑢))/2
𝑣_𝑎𝑣𝑒𝑟𝑎𝑔𝑒=𝑠/𝑡
𝑣_𝑎𝑣𝑒𝑟𝑎𝑔𝑒 = average velocity (ms-1)
𝑠 = displacement (m)
𝑡 = time (s)
𝑣_𝑎𝑣𝑒𝑟𝑎𝑔𝑒 = average velocity (ms-1)
𝑣 = final velocity (ms-1)
𝑢 = initial velocity (ms-1)

Question 4

What is vector subtraction
Example: An aeroplane changes course from 255ms^-1 west to 160ms^-1 east. Calculate the change in velocity of the aeroplane.

Answer 4

Δv=v2-v1
Δv=v2+(-v1)

v1: -255ms^-1
v2: 160ms^-1
Δv=160+(-255)
=415ms^-1 east

Question 5

Relative velocity formula
An airplane A flies to the north with a velocity of 350 m/s. An airplane B flies to the south with a velocity of 500 m/s beside airplane A. Calculate:
a) The relative velocity to the airplane A respect airplane B
b) The relative velocity to the airplane A respect airplane B, but now both fly to the north

Answer 5

Relative velocity = velocity of the body A – velocity of the body B
a) vAB = vA – vB = 350 m/s – (- 500 m/s) = 850 m/s or 850 m/s North

b) vAB = vA – vB = 350 m/s – 500 m/s = -150 m/s or 150m/s South