Mechanics Flashcards
(24 cards)
What is a vector in physics?
A vector is an arrow that shows the direction and magnitude of a force.
What is a resultant force?
The resultant force is found by adding the vectors of two forces acting on an object. If they go in opposite directions, one must be negative.
How do you find the resultant force when vectors are at right angles?
You use Pythagoras’ theorem to find the resultant.
What is a scalar?
A scalar is a measurement or quantity that has magnitude but no direction.
What is displacement?
Displacement is distance traveled with a direction.
What is the relationship between weight and gravitational force?
Weight is the force due to gravity acting on an object, calculated by multiplying mass by gravitational field strength (g).
On Earth, g is approximately 9.8 newtons per kilogram.
What is the equation for work done?
Work done equals force times distance moved.
What is gravitational potential energy (GPE)?
GPE gained is equal to mass times g times height (mgh).
What is the relationship between power and work?
Power equals work done per time, or power equals force times velocity.
What does Newton’s first law state?
When there’s no resultant force, an object’s motion is constant.
What does Newton’s second law state?
The resultant force is equal to mass times acceleration (F = ma).
What does Newton’s third law state?
For every action of force, there is an equal and opposite reaction force.
What happens to an object on a slope?
Its weight tries to pull it downwards while the reaction force of the slope pushes perpendicular to the slope.
How do you find the resultant force on an object?
The resultant force is the sum of all forces in one direction minus the sum of all forces in the opposite direction.
What is momentum?
Momentum is equal to mass times velocity.
What is the unit of momentum?
The unit of momentum is kilogram meters per second.
What is impulse?
Impulse is the change in momentum.
What is a couple in physics?
A couple is two forces pushing in opposite directions that produce a resultant moment but no resultant force.
What is the principle of moments?
For an object to be in equilibrium, the sum of clockwise moments must equal the sum of anti-clockwise moments.
What is a couple in physics?
A couple is defined as two forces pushing in opposite directions on an object such that they produce a resultant moment but no resultant force.
What happens to an object when a couple is applied?
The object will start to spin if it wasn’t already, but it will not accelerate.
What condition must be satisfied for an object to be in equilibrium?
An object is not in equilibrium if it only satisfies one of the two conditions.
What causes an object to topple over?
An object will topple over if its center of gravity is moved past the pivot vertically.
What changes when an object topples?
The moment due to its weight has changed direction from clockwise to anticlockwise or vice versa.
