forces - Physics

Question 1

What is a scalar quantity?

Answer 1

A quantity that only has magnitude (size)

Question 2

What is a vector quantity?

Answer 2

A quantity which has both magnitude (size) and direction

Question 3

List 3 scalar quantities

Answer 3

• speed
• temperature
• power

Question 4

List the 6 vector quantities

Answer 4

• displacement
• force
• velocity
• acceleration
• weight
• momentum

Question 5

What is the difference between a contact and a non-contact force?

Answer 5

a contact force is when objects physically collide to produce force, where as a non-contact force is when objects do not physically collide to produce force

Question 6

What is the resultant force?

Answer 6

The force that is the result of the sum of two opposing forces

Question 7

What is the centre of mass?

Answer 7

The point in an object in which all of the matter is concentrated to

Question 8

What does it mean when forces are in equilibrium?

Answer 8

The opposing forces produce the same amount of force, causing the resultant force to be 0N.

Question 9

In a distance-time graph, if the line is diagonal with a positive correlation, what is the object’s movement like?

Answer 9

constant speed

Question 10

In a distance-time graph, if the line is horizontal, what is the object’s movement like?

Answer 10

still, not moving

Question 11

In a distance-time graph, if the line is curved with a positive correlation, what is the object’s movement like?

Answer 11

accelerating

Question 12

What is displacement?

Answer 12

The distance travelled by an object in a given direction

Question 13

What is the difference between velocity and speed?

Answer 13

Speed measures distance and time, while velocity measures distance, time and direction

Question 14

What is acceleration?

Answer 14

a measure of the rate of change of velocity in a moving object

Question 15

Give the worded equation to the basic acceleration equation.

Answer 15

change in velocity (m/s)
Acceleration (m/s²) = ———————————
time taken for change (s)

Question 16

Give the letter equation for the basic acceleration equation.

Answer 16

v - u
a = ——
t

Question 17

In a velocity-time graph, if the line is diagonal with a positive correlation, what is the object’s movement like?

Answer 17

accelerating

Question 18

In a velocity-time graph, if the line is horizontal, what is the object’s movement like?

Answer 18

moving at a constant speed

Question 19

What does Newton’s first law state?

Answer 19

An object at rest will remain at rest, and an object at a constant speed will remain a constant speed and in the same direction, unless acted upon by an unbalanced force.

Question 20

What does Newton’s second law state?

Answer 20

The acceleration of an object is directly proportional to the resultant force of an object, and the acceleration of an object is inversely proportional to the mass of an object.

Question 21

Give the equation related to Newton’s second law.

Answer 21

Force (N) = mass (kg) x acceleration (m/s²)

Question 22

What is inertia?

Answer 22

The tendency of a moving or stationary object to continue on its course or stay stationary.

Question 23

If an object has lots of inertia, this means that it will be _______ to accelerate the object.

Answer 23

harder

Question 24

If an object has little inertia, this means that it will be _______ to accelerate the object.

Answer 24

easier

Question 25

Give the equation for inertial mass.

Answer 25

force (N) inertial mass = ————————— acceleration (m/s²)

Question 26

Describe why objects reach terminal velocity.

Answer 26

As an object is falling, its drag force increases as it speeds up, because of the object pushing more air particles out the way. This comes to a point where the drag force is equal to the weight of the object, causing the forces to be in equilibrium. As there is no other forces acting upon the object, the object will continue to fall at the same speed.

Question 27

When an object is falling, its velocity increases but its acceleration decreases. Explain why.

Answer 27

The object increases velocity because of the force of gravity acting upon it, however it deceases acceleration as there is increasing air resistance as velocity increases, causing the rate of change of velocity to decrease.

Question 28

What is the stopping distance of a car?

Answer 28

the distance between when a driver spots an obstacle and when the car stops

Question 29

What is the thinking distance?

Answer 29

Distance travelled during the reaction time of a driver

Question 30

What is the braking distance?

Answer 30

The distance travelled while the brakes are applied

Question 31

Label the 2 factors that affects thinking distance.

Answer 31

- initial velocity - reaction time of driver

Question 32

Label the 3 factors that affects braking distance.

Answer 32

- initial velocity - mass of vehicle - amount of brake force

Question 33

Give the worded equation to the motion acceleration equation.

Answer 33

final velocity (m/s) - initial velocity (m/s) acceleration (m/s²) = —————————————————— distance travelled (m)

Question 34

Give the letter equation to the motion acceleration equation.

Answer 34

v - u a = ——— s

Question 35

Give the equation for momentum.

Answer 35

momentum (kg m/s) = velocity (m/s) x mass (kg)

Question 36

Give the letter equation for momentum.

Answer 36

p = mv

Question 37

Why does a gun recoil?

Answer 37

Because of the conservation of momentum, a gun’s and bullet’s total momentum must equal 0 after the gun is fired. As the bullet shoots in a positive momentum in one direction, the gun must cancel out the momentum in the opposite direction. Therefore, it has a negative velocity to cancel out the momentum of the bullet, making the gun have recoil.

Question 38

What does the conservation of momentum state?

Answer 38

The initial momentum of must be equal to the final momentum after an event in a closed system.

Question 39

What does Newton’s third law state?

Answer 39

When two objects interact, the forces they exert on each other are equal and opposite.