P5b - Vectors and Equations of Motion

Question 1

What is the difference between a vector and scalar?

Answer 1

A vector includes direction and size, whilst a scalar does not take direction into account.

Question 2

How does velocity differ slightly to speed?

Answer 2

It involves direction.

Question 3

What do ‘+’ and ‘-‘ indicate, in terms of velocity.

Answer 3

• • = forward motion.
• • = backwards motion.

Question 4

What is relative velocity?

Answer 4

Compares the velocity of different vehicles.

Question 5

If one car has a speed of 30m/s in one direction and another car has a speed of 20m/s in the opposite direction, what is the relative velocity?

Answer 5

30 - - 20 = 50m/s

Question 6

What is the equation for average speed?

Answer 6

average speed = distance/time

Question 7

What are the four equations of motion?

Answer 7

• v=u+at
• s=(u+v)t/2
• v²=u²+2as
• s=ut+½at²

Question 8

What do the following letters represent for the equations of motion?

• s
• t
• u
• v
• a

Answer 8

• s = distance
• t = time
• u - initial velocity (speed)
• v = final velocity (speed)
• a = acceleration

Question 9

What can you assume the acceleration and inital velocity of a falling object is? Why?

Answer 9

• a = 10m/s/s as that is acceleration due to gravity on Earth.
• u = 0 because it wasn’t moving at the start.

Question 10

A boat is moving forward at the rate of 4m/s, but at the same time, the wind is blowing it sideways at the rate of 3m/s. What is its overall motion?

Answer 10

• By pythagoras: a² + b² = c²
• Therefore, overall motion² = 3² + 4² = 25
• overall motion = 5m/s