Dynamics Flashcards
Definition of Newton’s 1st law
Newton’s first law states that an object remains at rest or continues to move with a constant velocity unless an external resultant force acts on it.
Key points:
1)No resultant force is required to allow an object to continue its original motion.
2)Only forces that are exerted by other objects can change the state of motion of the object.
A coin is resting on a card on top of a cup. How can the coin be inside the cup without touching the coin and the cup?
The card has to be flicked during which the coin continues to stay its state of rest momentarily. Without the card’s support, the coin drops into the glass, due to its own weight.
How does friction affect the resultant force opposing the motion of the object?
With less friction, there is a smaller horizontal resultant force opposing the motion of the object. Hence, the object stops at a further distance.
Relationship between mass and inertia
The larger the mass of the object, the greater the inertia.
Definition of mass
Mass is the property of an object which resists change in its motion.
Definition of weight
Weight is the force experienced by a mass in a gravitational field.
SI unit of mass and weight
Mass: Kilogram(kg)
Weight: Newton(N)
Physical quantities of mass and weight
Mass: Scalar
Weight: Vector
Is the magnitude of mass fixed or variable?
Fixed
Is the magnitude of weight fixed or variable?
Variable, depends on gravitational field strength
Definition of apparent weight
Refers to the reading shown on a measuring instrument
Definition of weightlessness
Weightlessness refers to a sensation whereby we do not experience contact forces and it does not mean that there is no weight acting on us.
What are the forces acting on the object during weightlessness?
No other forces other than the weight
Definition of Newton’s 3rd law
Newton’s third law states that the forces of action and reaction between interacting objects are equal in magnitude but opposite in direction, of the same type and act on opposite bodies.
Definition of linear momentum
Linear momentum is the product of the object’s mass and its linear velocity.
Formula of linear momentum and what does it mean?
p = mv
The faster the object is moving or the more mass it possesses, the greater the momentum it has in the direction of motion.
What physical quantity is linear momentum?
Vector
What is the direction of linear momentum?
Its direction is the same as its velocity.
Definition of resultant force
Resultant force is the rate of change of momentum it imparts on an object.