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Physics chapter 2
Question | Answer |
---|---|
How is balance important in our lives? | Relationships- family and friends Finances- expenses and earnings nature- energy radiated by the earth and solar energy input from the sun |
what does mechanical equilibrium mean? | forces are balanced so no change in motion |
Motion would be changed if there was ___ | unbalanced external force |
Why is a force needed with an object? | to change its state of motion |
what is a force? | a push or pull |
a state of motion may be __? | at rest or moving |
if a hockey puck is not moving remains until a force hits it. it is? | at rest |
hockey puck sliding along ice until a force stops it is? | moving |
what is the combination of all forces acting on an object? | net force |
How many forces does a net force have acting on an object? | usually more than one |
what does a net force do? | changes the motion of an object |
What is the scientific unit of force? | Newton |
What does net force depend on? | Magnitude and direction of all applied forces |
If you push a rock up as hard as gravity is pulling down what happens? | rock does not move |
If you push harder than gravity on the rock upward what happens? | the rock goes upward |
if you push with less force on the rock what happens? | the rock moves downward |
what is tension? | the upward force acting on a suspended object |
what is tension sometimes called? | a stretching force |
what is the downward force caused by gravitational pull? | weight |
if two forces are equal and opposite, what is the net force? | zero |
if the net force is zero then what does the object do? | remains at rest |
how are vectors produced? | when the arrow is scaled to represent the amount of the force and the direction of the arrow points in the direction of the force |
what is a vector? | an arrow that represents both magnitude and direction of a quantity |
what does a vector quantity need? | both magnitude and direction for a complete direction |
what is a scalar quantity? | a quantity that can be described by magnitude only and has no direction |
what are some examples of scalar quantities? | time, area, and volume |
What can scalar quantities do? | can be added, subtracted, multiplied or divided like ordinary numbers |
when applied forces act in the same way what do u do? | add them |
when applied forces are acting in opposite directions what do u do? | subtract |
what is a state where no physical changes occur? | mechanical equilibrium |
EF=0 | equilibrium rule |
what is EF=0? | "when the sum of the forces acting on an object is zero the object is in mechanical equilibrium |
what should the sum or suspended objects equal in equilibrium? | zero |
If upward forces are positive and downward forces are negative what does the sum equal? | zero |
Equilibrium is either at rest or | at constant speed ina straight line path |
if an object has one force on it what is happening? | it cannot be in equilibrium |
what is one force acting on the object doing? | pushing |
the second force is acting in the opposite direction is the force of ____ | friction |
what does objects that are at rest said to be? | in static equilibrium |
objects moving at a constant speed in a straight line path are said to be in what? | dynamic equilibrium. |
what is a car on cruise control? | dynamic |
what is a girl hanging from a trapeze? | static |
what is a flower pot on a window sill? | static |
what is a hockey puck sliding across the ice? | dynamic |
what is an airplane in flight? | dynamic |