# Physics-20

Flashcards by j zed, updated more than 1 year ago
 Created by j zed about 6 years ago
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### Description

Unit I: Kinematics

## Resource summary

 Question Answer which ball will hit the ground first? they will hit the ground at the same time. REASONING: the vertical acceleration component of both balls is the same, regardless of the initial horizontal velocity of each ball. (ball 2's horizontal velocity has no affect on its vertical velocity.) what is the Cartesian method? a system for measuring directions (in terms of angles) using the x- and y-axis displacement a change in the position of an object including magnitude AND direction navigator method a system for measuring directions using compass bearings EG. 45 degrees south of east. position the straight-line distance and direction of an object from the origin NOTE: different from the displacement in that displacement is a change in position. what is a scalar quantity? a measurement that has only magnitude what is a sign convention? a system for designating directions along a straight line; one direction is positive and the other is negative EG. a compass rose what is a vector quantity? a measurement that has a magnitude and a direction EG. velocity what is acceleration? a measure of the rate of change of velocity, in relation to time what is distance? the length of the path taken to move from one place to another. not necessarily a straight line. what is speed? a measure of the distance travelled per unit of time. EG. m/s what is velocity? a measure of the rate of change of position in relation to time EG. m/s [N] what is one-dimensional motion? motion in a straight line what is uniform motion? motion at constant speed in a straight line what is accelerated motion? motion of an object that is either increasing or decreasing in speed or changing direction what is the instantaneous velocity? the velocity of an object at an instant of time what is kinematics? the study of motion without concern for forces, masses, or energy what is the parallelogram method? a method of adding vectors: the two vectors’ tails start at the same point and form sides of a parallelogram. the diagonal of the parallelogram that starts where the tails meet is the resultant (blue). what is the resultant? a vector sum of two or more other vectors. what is the tip-to-tail method? a method of adding vectors: the second vector (yellow) begins at the end of the first vector (red). the resultant (blue) is from the tip of the first vector to the tail of the second vector. what is a projectile? a moving object acted on by no forces other than gravity Newton's First Law an object at constant velocity remains in constant velocity until an unbalanced force is applied Newton's Second Law the net acceleration is proportional to the net force thus, Fnet = m(anet) Inertia (2 points) a measure of mass the amount of resistance to acceleration Centripetal Force the sum of all forces acting towards the centre. not always the same as net force. what does it mean when there is 0 tension at the top of a rope during centripetal motion? Fc = Fg what does Fc = Fg mean? (centripetal motion) (2 points) you're at the top of the circle you're going at the minimum speed required to stay on track centripetal force will not change as long as— the object is moving in a circle at at constant velocity "an object at rest stays at rest until another force acts on it" is an example of which law? Newton's First Law "Fnet = m(anet)" is an example of which law? Newton's Second Law Law of Elliptical Orbits planets orbit the sun in elliptical orbits with the sun at one of the foci (there is nothing at the other focus) Law of Equal Areas planets trace out equal areas in equal times Newton's Third Law for every action force, there exists a reaction force that is equal in magnitude but opposite in direction. net force vs total force net force is the sum of the forces acting on an object, including direction. net force is a vector. total force disregards the direction. In Newton’s third law, the two forces not only act in different directions, they also act on different ________. objects How can it be possible that objects exert forces on each other without contact? Gravity! If everything exerts a force on each other, how come things fall to Earth instead of Earth coming to them? Magnitude of acceleration is inverse to mass, so the rate of acceleration of such a huge object is negligible.

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