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29 Cards in this Set
- Front
- Back
- 3rd side (hint)
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A force field is a.... |
...region in which an object experiences a force. |
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The centre of gravity of an object is... |
The single point at which the weight of a body appears to act. |
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Weight of an object is... |
The vector sum of all gravitational forces acting on the individual elements of the object. |
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Types of noncontact forces |
Electric Field Magnetic Field Gravitational Field |
3 fields |
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Types of Contact forces |
Spring Force Tension Force Normal contact force Frictional Force Viscous Force |
There are 5 of them |
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Hookes Law definition |
the magnitude of force F exerted by a spring on a body attached to the spring is proportional to the extension x of the spring from equilibrium provided the limit of proportionality of the spring is not exceeded. |
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Formula of Hookes Law |
F=kx |
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State the magnitude and direction of tension |
Magnitude varies according to the extension for springs, Direction of tension on object is always in the direction of the stribg, rope or cable and away from the object |
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Magnitude and direction if N force |
Magnitude depends on how much force it exerts on the surface. Direction is always perpendicular to the contact surface and its direction is through the object of interest |
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Frictional force magnitude and direction |
Magnitude depends on the nature of the contact surfaces and the N force Direction is opposite to the intended/actual motion of the objecy and parallel to the surface |
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Magnitude and direction of viscous force |
Increases with velocity and cross-sectional area of the object as well as viscosity of fluid it is in Direction is opposite to motion of object |
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Guide to drawing a free body diagram (point mass) |
1. Identify object of interest 2. Draw other things that touch the object 3. Circle your object 4. Label contact forces exerted on object 5. Label non contact forces 6. Draw FBD |
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Definition if moment of a force |
It is the product of the magnitude of the force F and the distance d of the line of action of the force to the point. |
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Formula of moment of a force |
Tau= F x perpendicular distance Or Tau= Frsin(theta) |
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Couple definition |
" is a pair of force of equal magnitude but opposite in direction acting on object with parallel lines of action, producting only rotation. |
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Torque of a couple definition |
Torque of a couple is the product of one of the forces and the perpendicular distance between the lines of actions of the force. |
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Equilibrium occurs... |
... when there is no resultant force in any direction and there is no resultant torque about any point. |
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Translational equilibrium conditions |
1. Summation of forces acting on the object is zero. 2. Vector addition yields a closed polygon. 3. The linear acceleration of object is zero. |
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Rotational equilibrium means... |
That an object is not rotating or rotating at a constant angular velocity. |
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Principle of moments states that... |
for an object to be in rotational equilibrium, the sum of clockwise moments about any pivot must equal the sum of anti clockwise about that pivot |
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Static equilibrium conditions |
1. No resultant force in any direction 2. No resultant torque at any point. |
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Steps in solving static equilibrium problems |
1. Identify object. 2. Coordinate system for Fnet and acceleration 3. Draw an Free body diagram (extendrd mass) showing 4. Set up two force equations 5. Set up torque equation 6. Solve the equation to find unknown forces |
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Three forces in a translational equilibrium should.... |
...form a closed triangle. |
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Three forces in rotational equilibrihm should... |
Pass through the same common point. |
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Pressure due to fluid is... |
...the firce acting per unit area by the fluid |
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Formula of Pressure due to fkuid at a point. |
p=h(roe)g |
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Uptheust acting on an object in a fluid is... |
...net upward force due to the pressure difference on the upper and lower areas of the object by the fluid |
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Archimedes Principle states that... |
upthrust acting on a body, partially or totally immersed in a fluid is equal to the weight of the fluid displaced by the body. |
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The Law of floatation states that... |
when an object is in equilibrium, the weight of the fluid displaced by the object equals the weight of that object. |
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