B: Physics = Changes in Motion 1.8 A Closer Look at Braking Flashcards
What is the role of traction between tires and the roadway?
It plays a significant role in the ability of a vehicle to decelerate
Inadequate traction can lead to dangerous situations such as sliding through intersections.
What causes a vehicle to be unable to decelerate on icy roads?
The force of friction between the vehicle’s tires and the road is too low
This results in a lack of control over the vehicle’s movement.
What is the purpose of the raised tread pattern on a tire?
To reduce slippage and allow the tire to effectively grip the road
This is essential for both braking and moving the vehicle.
How is friction classified?
As a push or a pull measured in newtons
It is considered a vector quantity because it has both magnitude and direction.
What force pulls down on an apple held in a hand?
Gravity with a force of about 1 N
This is an example of a force acting on an object.
What can be required to stop a vehicle traveling at high speeds?
Thousands of newtons of force acting in the direction opposite to the velocity vector
This is necessary to bring the vehicle to a stop promptly.
What happens when a vehicle coasts at low speed on a level roadway?
Only hundreds of newtons of frictional forces from air and road resistance are produced
This is insufficient to stop the vehicle quickly.
What are the three frictional forces present when a vehicle is braking?
- Force of air resistance
- Force of road resistance
- Force applied by the braking system
These forces act together to decelerate the vehicle.
What is the term used to describe the sum of all forces acting to slow the vehicle?
Net force
In this context, ‘net’ refers to the total of all forces acting in the same direction.
Fill in the blank: Friction is a push or a pull that is measured in _______.
newtons
True or False: The raised tread on tires is designed to increase slippage.
False
The raised tread is specifically designed to reduce slippage.
What role does traction between tires and the roadway play in vehicle deceleration?
It plays a significant role in the ability of a vehicle to decelerate
Insufficient traction can lead to vehicles sliding through intersections.
What is a common experience indicating low deceleration ability in vehicles?
Sliding straight through an intersection
This usually happens on icy winter roads.
What factor largely determines a vehicle’s deceleration on slippery surfaces?
The force of friction between the vehicle’s tires and the road
Low friction can prevent effective deceleration.
What is the purpose of the raised tread pattern on a tire?
To reduce slippage and allow the tire to effectively grip the road
This friction is necessary for braking and moving the vehicle.
How is friction classified in physics?
As a vector
A vector is a quantity that has both magnitude and direction.
What is the approximate force with which gravity pulls down on a small apple?
About 1 N
N stands for newton, the unit of force.
How many newtons of force may be needed to bring a vehicle to a stop?
Thousands of newtons
This is particularly true when the vehicle is moving at high speeds.
What happens when a vehicle coasts at low speed on a level roadway?
It experiences only hundreds of newtons of frictional forces
These forces come from air and road resistance.
What are the three frictional forces present when a vehicle is braking?
- Force of air resistance
- Force of road resistance
- Force applied by the braking system
The combination of these forces contributes to the vehicle’s deceleration.
What is the term used to describe the sum of all forces acting on a vehicle during braking?
Net force
In this context, ‘net’ means the total of all acting forces.
True or False: The net force during braking always acts in the direction of the vehicle’s motion.
False
The net force acts in the opposite direction to slow the vehicle down.
What is mass?
The quantity of matter in an object
Mass is a scalar quantity usually measured in kilograms.
How does the mass of a vehicle affect deceleration?
A vehicle’s mass affects the rate of deceleration, with larger masses requiring earlier deceleration
A transport truck has a mass that is many thousands of kilograms greater than a typical passenger car.
True or False: A truck driver must start the process of deceleration sooner than a passenger car driver when approaching a red light.
True
This is due to the greater mass of the truck.
Fill in the blank: The mass of a transport truck is many thousands of kilograms greater than that of a _______.
typical passenger car
What is Newton’s Second Law of Motion?
A law stating that an object will accelerate in the direction of the net force.
What is the equation that expresses Newton’s Second Law of Motion?
F = ma
In the equation F = ma, what does ‘F’ represent?
‘F’ represents net force.
In the equation F = ma, what does ‘m’ represent?
‘m’ represents mass.
In the equation F = ma, what does ‘a’ represent?
‘a’ represents acceleration.
What are the units of force in the context of Newton’s Second Law?
N = (kg) (m/s²)
Fill in the blank: The unit of force, the newton, is defined in terms of the equation _______.
F = ma
True or False: Newton’s Second Law can be expressed in terms of acceleration instead of net force.
True
What does the term ‘net force’ refer to in Newton’s Second Law?
The overall force acting on an object after all the forces are combined.
What is the relationship between the direction of the net force and acceleration when braking a vehicle?
Both oppose the motion of the vehicle in the positive direction.
When braking, how are the net force and acceleration described in relation to the vehicle’s motion?
They are negative.
True or False: During braking, the net force and acceleration act in the same direction as the vehicle’s motion.
False.
