# FORCES REVISION

Flashcards by Ursula Brown, updated more than 1 year ago
 Created by Ursula Brown over 7 years ago
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### Description

Bachelors Degree PHYSICS (10 ADVANCED SCIENCE - Forces) Flashcards on FORCES REVISION, created by Ursula Brown on 09/07/2013.

## Resource summary

 Question Answer VELOCITY Velocity is the rate of change in displacement over time. $\frac{change in displacement}{time}$ $v_{av}$=$\frac{$$\delta$$s}{t}$ $v_{av}$=$\frac{u+v}{2}$ v=u+at ACCELERATION Acceleration is the rate of change in velocity over time. a=$\frac{change in velocity}{time}$ a=$\frac{$$\delta$$v}{t}$ a=$\frac{v-u}{t}$ a=$\frac{\[F_net$ }{m}\] VECTOR A quantity which has both magnitude and direction. SCALAR A quantity which has only magnitude (no direction). ACCELERATION DUE TO GRAVITY The acceleration an object experiences during free-fall, caused by its attraction to the Earth. $a_g$=~9.8m$s^-2$ TERMINAL VELOCITY As an object falls, it picks up speed. The increase in speed leads to an increase in the amount of air resistance. Eventually, the force of air resistance becomes large enough to balances the force of gravity. At this instant in time, the net force is 0 Newton; the object will stop accelerating. The object is said to have reached a terminal velocity. The change in velocity terminates as a result of the balance of forces. The velocity at which this happens is called the terminal velocity. NEWTON'S FIRST LAW OF MOTION An object will remain in a state of uniform motion (if it is at rest, then the object will remain at rest), maintaining the same speed and direction (therefore velocity), unless acted upon by an external unbalanced force. NET FORCE The term Net Force refers to the force that does not become completely balanced (or cancelled) by the other individual forces. It is the vector sum of all forces acting on an object. If$F_net$=0, velocity is constant. NEWTON'S SECOND LAW OF MOTION $F_net$=ma An object will accelerate in the direction of a Net Force acting upon it. The size of this acceleration depends on the mass of the object, and the size of the acting force. NEWTON'S THIRD LAW OF MOTION For every action force, there is an equal and opposite reaction force. Action and reaction forces never act on the same object. Thus, they do not always have the same effect. INERTIA Inertia is the tendency of a body to resist a change in motion. Inertia is proportional to mass. A larger mass means a larger inertia. WEIGHT Weight is the gravitational attractive force the Earth exerts on a body. w=mg where $F_gravity$=w and $a_gravity$=g

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