Define the term force.
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Define the term force.
A force is a push or pull that arises from the interaction between objects.
What is the name of the force that arises due to gravitational attraction between objects with mass?
Weight is the force that arises due to gravitational attraction between objects with mass.
True or False?
Frictional forces always oppose the motion of the moving object.
True.
Frictional forces do always oppose the motion of the moving object.
True or False?
Drag is a type of gravitational force.
False.
Drag is a type of frictional force.
Drag occurs when an object moves through a fluid (a gas or a liquid).
True or False?
Air resistance is a specific type of drag force.
True.
Air resistance is a specific type of drag force. Air resistance occurs when objects move through air.
Define the term reaction force.
A reaction force is the force exerted on an object by the surface it is resting on. The reaction force acts at right angles to the surface.
True or False?
Upthrust always opposes the motion of an object.
False.
Friction always opposes the motion of a moving object. Thrust usually speeds up the motion of an object and therefore acts in the same direction as the object's motion.
True or False?
The electrostatic force acts between objects with magnetic poles.
False.
The electrostatic force acts between objects with charge. The magnetic force acts between objects with magnetic poles.
Name three effects that forces can have on objects.
The three effects that forces can have on objects are:
changing the object's speed
changing the object's direction
changing the object's shape
True or False?
Two like poles will experience a pull force.
False.
Two like poles will experience repulsion, which is a push force.
Define a scalar quantity.
A scalar quantity is a quantity that has magnitude but not direction.
What is a vector quantity?
A vector quantity is a quantity that has both magnitude and direction.
True or False?
Mass is a scalar quantity.
True.
Mass is a scalar quantity as it has only magnitude.
True or False?
Distance is a vector quantity.
False.
Distance is a scalar quantity.
Is 300 N a scalar or vector quantity?
300 N is a vector quantity. Newtons (N) are the unit of force, and force has both magnitude and direction; therefore, force is a vector quantity.
Is 100 km due north a scalar or a vector quantity?
100 km due north is a vector quantity because it includes both a magnitude and a direction.
True or False?
Energy is a scalar quantity.
True
Energy is a scalar quantity. It has magnitude, but not direction.
Is temperature a scalar or a vector?
Temperature is a scalar quantity.
True or False?
Weight is a scalar quantity.
False.
Weight is a force, so it is a vector quantity. Mass is a scalar quantity.
What is the difference between speed and velocity?
Speed is a scalar quantity with only magnitude. Velocity is a vector quantity with both magnitude and direction.
Define a resultant force.
A resultant force is a single force that represents the combined effect of all forces acting on an object. It determines both the direction and the magnitude of the overall force experienced by the object.
A force of 10 N acts on an object to the left. A force of 7 N acts on the same object to the right. What is the resultant force on the object?
The resultant force on the object is 3 N to the left.
The reaction force of a chair on a person is 600 N upward. The weight force on the person is 600 N downward. What is the resultant force on the person in the chair?
The resultant force of the person in the chair is zero. The weight force and the reaction force are of equal magnitude and opposite in direction; therefore, the forces are balanced, so there is no resultant force.
The resultant force on a moving car is zero. The driving force is 2000 N. What is the sum of the resistive forces acting on the car?
If there is no resultant force acting on the car, then the forward and backward forces must be equal. Therefore, if the driving force is 2000 N, then the sum of the resistive forces must also be 2000 N.
True or False?
When the resultant force is zero, the forces acting on an object are balanced.
True.
When the forces acting on an object are balanced, there is zero resultant force.
State the equation for the resultant force, mass, and acceleration.
The equation for the resultant force is
Where:
= resultant force, measured in newtons (N)
= mass, measured in kilograms (kg)
= acceleration, measured in metres per second squared (m/s2)
What is the symbol for resultant force?
The symbol for resultant force is .
What are the units for resultant force?
The units for resultant force are newtons (N).
A car is moving in a forward direction. The resultant force acts in a backward direction. Describe the motion of the car.
The car is travelling forward, but the resultant force acts in the opposite direction to the motion of the car. This means that the car is decelerating or slowing down.
True or False?
Mass is a vector quantity.
False.
Mass is a scalar quantity.
The S.I. unit for mass is kg. What does kg stand for?
The S.I. unit kg stands for kilograms.
Define weight in terms of the effect of a gravitational field.
Weight is the effect of a gravitational field on an object with mass.
State the symbol for gravitational field strength.
The symbol for gravitational field strength is .
True or False?
Weight is a measure of the quantity of matter in an object.
False.
Mass is a measure of the quantity of matter in an object. Weight is a gravitational force on an object with mass.
True or False?
An object's mass varies depending on the gravitational field strength.
False.
An object's mass is independent of gravitational field strength.
How is weight affected by the gravitational field strength?
The stronger the gravitational field, the greater the weight force exerted on an object.
What is the name of the force that causes objects to fall to the ground?
Weight is the force that causes objects to fall to the ground.
State the equation for weight.
The equation for weight is
Where:
= weight force, measured in newtons (N)
= mass, measured in kilograms (kg)
= gravitational field strength, measured in newtons per kilogram (N/kg)
True or False?
The mass of an object and the weight force acting on it are directly proportional.
True.
The mass of an object and the weight force acting on it are directly proportional. This means that doubling the mass will also double the weight force acting on the object.
Define the stopping distance of a car.
The stopping distance of a car is the total distance travelled during the time it takes a car to stop in an emergency.
State the equation used to calculate the stopping distance of a car.
The equation used to calculate the stopping distance of a car is
What are the units for stopping distance?
The units for stopping distance are metres (m).
Define thinking distance.
Thinking distance is the distance travelled in the time it takes the driver to react to an emergency and prepare to stop.
What are the two factors affecting thinking distance?
The two factors affecting thinking distance are:
the speed of the car
the reaction time of the driver
Define reaction time.
Reaction time is a measure of how much time passes between seeing something and reacting to it.
State three factors that can increase a driver's reaction time.
Three factors that can increase a driver's reaction time are:
tiredness
distractions
intoxication
Define braking distance.
Braking distance is the distance travelled under the breaking force (of the car). This is the distance travelled by the car during the time the breaks are applied.
What are the four factors affecting stopping distance?
The four factors affecting stopping distance are:
vehicle speed
vehicle mass
road conditions
driver reaction time
Define acceleration of free fall.
Acceleration of free fall is the constant rate at which all objects fall in the absence of air resistance, typically denoted by the symbol and equal to approximately 10 m/s² near the surface of the Earth.
True or False?
All objects fall with the same acceleration in the presence of air resistance.
False.
In the presence of air resistance different objects fall at different accelerations and not at g. In most Physics questions we assume that air resistance is negligible.
True or False?
Acceleration of free fall remains constant regardless of an object's mass.
True.
Acceleration of free fall remains constant regardless of an object's mass.
Define terminal velocity.
Terminal velocity is the fastest constant speed a falling object can reach. Terminal velocity is reached when the upward force of air resistance equals the downward force of weight, resulting in zero acceleration.
True or False?
Air resistance decreases as the speed of a falling object increases.
False.
Air resistance increases as the speed of a falling object increases.
Define air resistance.
Air resistance is the frictional force exerted by air particles on objects moving through air, which opposes the direction of motion.
How does air resistance affect the motion of falling objects?
Air resistance opposes the motion of objects falling through air, exerting an upward force that increases with the object's speed.
What is the relationship between the forces of weight and air resistance during free fall? (Extended Tier Only)
During free fall, weight acts downwards while air resistance acts upwards. As the speed of the object increases, air resistance increases until it equals the weight and terminal velocity is reached.
How does terminal velocity affect the acceleration of a falling object?
Terminal velocity occurs when the acceleration of a falling object becomes zero because the upward drag force equals the downward force of weight, resulting in a constant speed.
True or False?
Air resistance remains constant during the fall of a skydiver.
False.
The air resistance changes with speed during the fall of a skydiver.
What factors affect the acceleration of freefall?
The acceleration of free fall is equal to gravitational field strength. It is independent of the mass of the falling object.
Define Hooke's Law.
Hooke’s law states that the extension of a spring is proportional to the applied force, up to the limit of proportionality.
True or False?
Hooke's Law states that the extension of a spring is inversely proportional to the applied force.
False.
Hooke's Law states that the extension of a spring is directly proportional to the applied force.
What does the green arrow represent on this force-extension graph?
The green arrow shows the linear portion of the graph. This is the section that obeys Hooke's law, where force and extension are directly proportional.
What does the green arrow represent on this force-extension graph?
The green arrow shows the non-linear section of the graph where Hooke's law is not obeyed. Force and extension are no longer proportional.
What does the red cross represent on this force-extension graph?
The red cross represents the limit of proportionality. Beyond this point, force and extension are no longer directly proportional.
What is the elastic behaviour of a material?
The elastic behaviour of a material is its ability to recover its original shape after the forces causing the deformation are removed.
True or False?
Deformation is a change to the original shape of an object that can be temporary or permanent.
True.
Deformation is a change to the original shape of an object that can be temporary or permanent.
True or False?
Elastic deformation is a permanent change to an object's shape.
False.
Inelastic deformation is a permanent change to an object's shape. Elastic deformation is a temporary change to an object's shape.