Test on Motion - Grade 9

Question 1

Actual Speed

Answer 1

The distance traveled by body at particular instant of time

Question 2

Speed

Answer 2

The average speed of an object is given by the ratio between distance travelled (usually in meters) and the time taken (usually seconds).

Distance/time

Question 3

Units for Speed

Answer 3

Kilometers per hours (km/h)
meters per second (m/s)
miles per hour (mph)

Question 4

Magic Triangle

Answer 4

d = t x v
v = d / t
t = d / v

Question 5

Velocity

Answer 5

Speed with direction

Question 6

Scalar

Answer 6

A quantity that is represented by a simple numerical value.

Example: mass, temperature, time

Question 7

Vector

Answer 7

A quantity that has a value (magnitude) as well as a direction.

Example: force, weight, velocity

Question 8

Acceleration

Answer 8

Occurs when there is a change in speed, or direction, or both = when there is a change of velocity.

Negative or positive

Vector

Question 9

When speed increases

Answer 9

positive acceleration

Question 10

When speed decreases

Answer 10

negative acceleration

Question 11

When changing direction…

Answer 11

speed is not changing
but
velocity is changing

Question 12

Find the final speed

Answer 12

Initial speed is zero: v = a x t
Initial speed is not zero: v = u + (a x t)

Question 13

Acceleration equation

Answer 13

(v - u) / t = a

Question 14

Acceleration symbol

Answer 14

acceleration = a

Speeding up
Slowing down
Changing direction

Question 15

Distance time graph

Answer 15

horizontal line = no movement

line going up = positive constant speed

line going down = negative constant speed

curved line going up = positive acceleration

curved line going down = negative acceleration

Question 16

how to find the speed in a distance time graph

Answer 16

rise over run

distance over time

Question 17

The slope in a distance time graph

Answer 17

the slope (gradient) of a line is numerically equal to the spread

Question 18

the slope in a speed time graph

Answer 18

the slope (gradient) of a line is numerically equal to the acceleration

Question 19

Speed time graph

Answer 19

horizontal line on the x axis = no movement

horizontal on pos. side = positive constant speed

horizontal on neg. side = constant negative speed

line going up = positive acceleration

line going down = negative acceleration

Question 20

To find the distance travelled

Answer 20

the area under the line is equal to the distance travelled

d = v x t

example: 10 x 15 = 150

find the area of the section

if it is a triangle than divide by 2

Question 21

Falling under gravity

Answer 21

When released any object will fall with increasing speed; acceleration

Object fall because of the force of gravity

The shape is more important than the weight because of air resistance

Question 22

Acceleration of free fall

Answer 22

without air resistance all objets will fall with the same acceleration, known as the acceleration of free fall or g

each the value is: g = 9.80665 ms -squared

Question 23

Motion under free fall

Answer 23

if an object is moving under free fall its velocity is given by: v = g x t

10t

the distance: d = 1/2 g time(squared)

5t squared