physics Flashcards
(26 cards)
What is inertia?
Inertia refers to the the natural tendency of an object to maintain its velocity, therefore resisting any changes in speed or direction. Inertia is NOT a force.
What is velocity?
An object’s speed and direction.
Examples of Inertia
An object at rest tends to stay at rest, and a moving object tends to keep moving with the same speed in the same direction.
What is a force?
A push, pull or twist.
What is a net force?
The total forces acting on a single object
How do you find the net force?
Add forces going in the same direction and subtract any forces acting in opposite directions.
What is the unit of force?
Newtons (N)
What is a balanced force?
When two forces have the same strength but opposite directions, so net force = 0
What is an unbalanced force?
A force is unbalanced if it causes an object to change its motion — meaning it speeds up, slows down, starts moving, stops, or changes direction.
What happens to objects with 0 net force?
They either stay at rest or keep moving with zero acceleration (they are constant)
What happens to object with a net force acting on it?
It accelerates in the direction of the net force.
What is Newtons’ second law?
F=ma, a=F/m, m=F/a
When force is halved/doubled…
Do the same to acceleration
If you double/halve mass then…
Do the opposite for acceleration
What are the standard units (for calculations)?
1N = 1kg x 1 m/s/s
What happens when units are smaller than standard?
Convert them
Why is different acceleration produced on objects with different masses?
Net force produces different accelerations on objects with different masses because the objects have different amounts of inertia. More mass = more inertia and force required to accelerate
Why does the acceleration of a rocket change as it rises through the atmosphere?
The rocket is decreasing in mass as it burns fuel to continue moving and the fuel load decreases, therefore so does its total weight. There’s also a decrease in downward forces as a rocket’s acceleration depends on its net force, although the upward thrust force doesn’t change, the downward forces of gravity and air resistance get weaker because of the thinner atmosphere and being further away from Earth’s centre.
What is Newton’s third law of motion?
Every force has an equal and opposite reaction force (if one object exerts force on another, the second exerts a force of the same size back)
What are the requirements for forces to be paired under Newtons third law?
That a force is paired with another force called a reaction force. The two forces must, be equal in size, be opposite in direction, be of the same type and act on different objects, to be paired under Newtons third law.
If forces have the same strength under Newton’s third law wouldn’t they cancel each other out?
That is only applied when they act upon the same object, pairs of forces always act on different objects and therefore can never be balanced.
Why is it that when a person kicks a ball the ball accelerates, yet they don’t?
When a person kicks a ball, they exert a force on the ball — and according to Newton’s Third Law, the ball exerts an equal and opposite force back on the person. But, because the ball has much less mass, it accelerates significantly, while the person’s much larger mass means their acceleration is so small it’s barely noticeable. This difference in acceleration is explained by Newton’s Second Law: the same force causes a greater acceleration in objects with less mass
What is gravity’s acceleration?
10m/s/s
What is the relationship between velocity and acceleration?
When velocity changes there is acceleration, when it doesn’t there isn’t
