Topic 2 - motion and forces

Question 1

Vector

Answer 1

a vector quantity has both magnitude (size) and
specific direction

Question 2

Scalar

Answer 2

a scalar quantity has magnitude (size) but no
specific direction

Question 3

Examples of scalar quantities

Answer 3

Temperature
mass
time
energy
speed
distance

Question 4

Examples of vector quantities

Answer 4

velocity
displacement
force
weight
acceleration
momentum

Question 5

What is velocity?

Answer 5

Speed in a stated direction

Question 6

How can a vector quantity be represented?

Answer 6

Vector arrows (length of arrow = magnitude).

Question 7

Average speed

Answer 7

Average speed = distance ➗ time
(m/s) (m) (s)

Question 8

average acceleration of an object

Answer 8

acceleration = change in time ➗ time taken
(m/s2) (m/s) (s)

Question 9

equation for velocity (with a displacement)

Answer 9

v − u = 2× a× x

Question 10

On a distance/time graph, what value does the gradient represent?

Answer 10

the speed

Question 11

How can you calculate the speed at a given time from a distance time graph for an accelerating object?

Answer 11

• draw a tangent to the curve at the required time
• calculate the gradient of the tangent

Question 12

On a displacement/time graph, what value does the gradient represent?

Answer 12

the velocity

Question 13

How can the distance travelled by an object be calculated from a velocity-time graph?

Answer 13

It is equal to the area under the graph

Question 14

On a velocity-time graph, what does the gradient of the graph represent?

Answer 14

The acceleration

Question 15

typical value for the speed of sound

Answer 15

330 m/s

Question 16

typical value for human walking speed

Answer 16

1.5 m/s

Question 17

typical value for human running speed

Answer 17

3 m/s

Question 18

typical value for human cycling speed

Answer 18

6 m/s

Question 19

approximate value for the acceleration of an object in free fall under gravity near the earth’s surface

Answer 19

10 m/s^2

Question 20

resultant force

Answer 20

the single force that is equivalent to all the other forces acting on a given object

Question 21

Newtons first law for a stationary object

Answer 21

If the resultant force on a stationary object is zero, the object will remain at rest

Question 22

Newtons first law for a moving object

Answer 22

If the resultant force on a moving object is zero, the object will remain the same at a constant velocity. (same speed, same direction).

Question 23

Newtons second law

Answer 23

Resultant Force = Mass x Force
F=MA

Question 24

Newton’s second law (in word)

Answer 24

An object’s acceleration is directly proportional to the resultant force acting on it and inversely proportional to its mass.

Question 25

Weight?

Answer 25

The force that acts on an object due to gravity and the object’s mass

Question 26

Weight equation

Answer 26

weight = mass x gravitational field strength

Question 27

What can be used to measure an object’s weight?

Answer 27

A calibrated spring-balance or newton-metre