3B1 Force their applications Flashcards
Learn the basics of forces in physics and their effects on objects.
What is force in simple terms?
An external agent that changes the state of rest or motion, direction, shape, or size of an object.
What is an applied force?
A push or pull exerted by one object on another.
Give an example of applied force.
- A person pushing a door open.
- A person pulling a suitcase on wheels.
How can an applied force affect an object?
It can change:
- the state of rest or motion
- direction
- shape
- size of the object
What are the characteristics of applied force?
- It results from interaction between objects.
- Has magnitude and direction.
- Can change the object’s state or shape.
What is meant by contact force?
A force that occurs when two objects are in physical contact.
What is a non-contact force?
A force exerted by an object on another without physical contact.
Give an example of a non-contact force.
- The gravitational pull of the Earth on objects.
- A magnet attracting metal object at some distance.
What is meant by ‘applied forces are vectors’?
Applied forces have both magnitude and direction.
Examples include force, velocity, and acceleration.
Explain what it means when we say that ‘applied forces are additive in nature’.
This means that when more than one force acts on an object, the resultant force is given by the vector sum of the individual forces.
For example, if two people push a box in the same direction with forces of 5N and 10N, the resultant force is 15N in that direction.
What happens when two equal forces act in opposite directions on an object?
The resultant force is zero.
List some examples of contact forces.
- Friction
- Air resistance
- Tension force
- Spring force
List some examples of non-contact forces.
- Gravitational force
- Electrostatic force
- Magnetic force
Calculate the resultant force on the object in the diagram.
5N - 5N = 0N
The resultant force is found by subtracting the opposing forces.
If forces are in opposite directions, you subtract their magnitudes. If they are in the same direction, you add them.
What is friction?
The force that arises when two surfaces rub over each other.
Friction always acts in the direction opposite to the motion, reducing the speed of moving objects.
What is air resistance?
A type of frictional force that acts on objects as they move through air.
Air resistance increases with the speed of the moving object and the surface area of the object.
Which force is acting on the rope that is being pulled on both sides?
Tension
Tension is the force transmitted through a string, rope, cable, or similar object when it is pulled tight by forces acting from opposite ends.
Which force is acting on the compressed spring?
Spring force
Spring force obeys Hooke’s Law, which states that the force exerted by a spring is directly proportional to its displacement from the equilibrium position.
What is electrostatic force?
The force between stationary electric charges.
How does gravitational force affect Earth and the Solar System?
It keeps planets revolving around the sun and objects stuck to Earth.
How does Earth’s gravity affect objects?
Gravity is a force that pulls objects toward the Earth’s center, giving them weight.
Weight is different from mass; weight is the force exerted by gravity on an object, while mass is the amount of matter in the object.
How does a non-contact magnetic force work in a refrigerator?
A magnetic strip on the door attracts the metallic body of the refrigerator, closing it.
How can applied forces be categorized?
- Contact forces
- Non-contact forces
How can applied forces change an object’s motion?
By altering its speed or direction.
Newton’s First Law states that an object will remain at rest or in uniform motion unless acted upon by an external force.
How does a baseball player apply force to the ball?
By hitting it, changing its direction of motion.
What force acts on a ball when caught by a football player?
The applied force stops the ball’s motion.
How do contact forces differ from non-contact forces in terms of distance?
- Contact forces act with zero distance between objects.
- Non-contact forces act over a distance.
What type of force is involved in pushing a heavy parcel?
Both contact (push) and non-contact (gravitational) forces.
What are forces measured in?
Newtons (N)
Explain how weight is a force.
It is the force exerted by gravity on an object’s mass, and it always acts downwards.
The weight of an object can be calculated by multiplying its mass (in kilograms) by the acceleration due to gravity (approximately 9.8 m/s² on Earth).
How do you determine the resultant force when multiple forces act on an object?
By calculating the vector sum of all individual forces acting on the object.
This involves adding forces that act in the same direction and subtracting forces that act in opposite directions.
What are balanced forces?
They are equal in magnitude and opposite in direction, keeping an object at rest or maintaining its constant velocity.
What are unbalanced forces?
They are forces in opposite directions that are not equal, causing an object to change velocity.
