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Physics Ch. 4
Question | Answer |
---|---|
Define force. | The cause of an acceleration, or the change in an object's velocity. |
Force can cause objects to do what? | Start moving, stop moving, or change direction. |
What is the unit of force? | Newton. |
Who is the newton named after? | Sir Isaac Newton. |
1 Newton= ? | (1kg)(1m/s^2) |
What are the two ways force can occur? | 1.) Contact. 2.) Field. |
Define contact force. | Force that arises from the physical contact of two objects. Ex- Catching a football. |
Define field force. | Force that can exist between objects, even in the absence of physical contact between the objects. Ex- Force of gravity. |
Define force diagrams. | A diagram of the objects involved in a situation and the forces exerted on the object. |
Is force a scalar or vector quantity? | Vector. |
Define net external force. | The total force resulting from a combination of external forces on an objects. A.K.A. resultant force. |
When on a flat surface, Fnorm is equivalent to what? | Fgravity. |
Define Newton's First Law. | An object at rest remains at rest, and an object in motion continues in motion with constant velocity unless the object experiences a net external force. |
Define inertia. | The tendency of an object to maintain its state of motion. |
Which has more inertia: a toy car or a real car? | A real car. |
______ is measurement of inertia. | Mass. |
Define equillibrium. | The state in which there is no change in a body's motion. |
Define Newton's Second Law. | The acceleration of an object is directly proportional to the net external force acting on the object and inversely proportional to the object's mass. |
Define Newton's Third Law. | For every action, there is an equal and opposite reaction. |
Define weight. | The magnitude of the force of gravity acting on an object. |
Define normal force. | A force exerted by one object on another in a direction perpendicular to the surface of contact. |
Define static friction. | The resistive force that opposes the relative motion of two contacting surfaces that are at rest with respect to one another. (Fs) |
Define kinetic friction. | The resistive force that opposes the relative motion of two contacting surfaces that are moving past one another. (Fk) |
Define coefficient of friction. | The ratio of the force of friction to the normal force acting between two objects. |
Which is more: static friction or kinetic friction. Why? | Static friction because Law of Inertia states it takes more force to put an object into motion than to keep it in motion. |