SAMPLE PROBLEM 2H A car accelerates from 5 m s1 east to 40 m s1 east in 5 s.What is its acceleration?
SAMPLE ANSWER 2H Using the formula for acceleration, making sure all values are in their standard unit:
The car is accelerating at 7 m s2 due east. a v u
t 40 5 5 35 5 7
EXERCISE 2.2 DISPLACEMENT, VELOCITY AND ACCELERATION
Q1 A girl runs at a speed of 7 m s1 for 20 s. How far has she travelled? Q2 A man travels north at an average velocity of 12 m s1.What is his displacement after 2 minutes? Q3 A bird travels at 40 km h1.How long does it take the bird to reach its nest 1 500 m away? Q4 What is the average velocity of a motorbike that is accelerating uniformly from 8 m s1 to 30 m s1 north? Q5 A car starts from rest and reaches a speed of 15 m s1 in 3 s. Calculate the car’s acceleration. Q6 A bus changes velocity from 30 m s1 to 10 m s1 in 8 s.What is its deceleration? Q7 A motorcycle accelerates from 36 km h1 to 90 km h1 in 5 s.What is its acceleration? Q8 The light year is the unit used for astronomical distances; it is the distance travelled by light in 1 year.The speed of light is 3 108 m s1.The Sun is 8.31 light minutes away. Alpha Centuri is the next nearest star to the Earth; it is 4.37 light years away. Andromeda is the nearest galaxy to the Milky Way; it is roughly 2.5 million light years away.Taking the average solar year as 365.25 days, calculate the distance:
(i) travelled by light in one year (ii) from the Earth to the Sun (iii) from the Earth to Alpha Centuri (iv) from the Milky Way to Andromeda
Equations of Motion
Sir Isaac Newton came up with a series of equations of motion that can be used for calculations involving constant accelerations.This type of motion, where the value of a does not change throughout the question (or at least distinct parts of the question), is called Linear Motion.
The ability to use these equations is required for both higher and ordinary level, while their derivations are for higher level only.
