FORCES Flashcards
What is a contact forces and its formula?
Is the resultant of the normal contact force and friction force
Related by the equation √[friction^2 + normal reaction ^2]
What are the 3 factors that affects viscous forces
Speed of an object
Viscosity of Fluid [❌density]
Shape and size of the object
What is the definition of viscous forces
a force that opposes relative motion when an object moves through a fluid
definition of friction
- can friction exist without motion
- does speed affect it
Friction always opposes relative motion between 2 surfaces in contact and is constant when object is moving
-can exist without motion
-no
what is tension and its direction
refers to the ‘pulling’ force exerted by a spring, string,cable,rope,rod etc on another object
Acts away from object, tension objects
what is compression and its direction
refers to the pushing force exerted by a column, rod etc on another object.
Acts away from object, tension objects
What is Hooke’s Law and its formula
If the limit of proportionality is not exceeded, the extension is directly proportional to the force/load applied
F = k x
where:
F is force applied
x is the extension or compression of material [Note: x is the change in length not the total length]
k is a constant of the proportionality or a force constant
[k] : Nm-1
Assuming springs are connected in series, What is the effective spring constant for springs?
In a series of springs, the force applied on all springs are equal.
Where eT =e1 + e2+ e3+…..
so kT = F/[ e1 + e2 + e3 + …..]
spring stretches independent
Assuming springs are connected in parallel, What is the effective spring constant for springs?
In spring arranged in parallel, the force applied on springs are shared.
Where FT = FA + FB + FC + ….
Extension(x) is the same for all springs regardless of k
Applying k = F/x
kT = [FA + FB + ….]/x
Springs are stretched depend on each other
What does a higher/lower spring constant indicate
higher k => spring constant increase
lower k => spring constant is smaller
What is Buoyancy Force?
It is an upward force exerted by the fluid on a submerged or floating object due to the difference in pressure between the upper and lower surfaces of the objects.
2 factors affecting Buoyancy force?
Density of fluid
- BF increases when object is immersed in denser medium
Volume of fluid displaced/submerged
- BF increases -> volume displaced increases
what is the definition of systematic error
systematic error is an error that consistently causes measurements to be either always larger or always smaller than the true value.
what is random error
it’s an error defined as a measured value that is either higher or lower than true value.
What is the definition of a force?
A force is a push or pull that acts on an object due to its interaction with another object. It is a vector quantity measured in newtons (N).
What is Hooke’s Law?
Hooke’s Law states that the force F exerted by a spring is directly proportional to its extension x
Define the moment of a force.
The moment of a force is the turning effect produced by a force about a pivot point
What is the torque of a couple?
Torque is the turning effect produced by a couple
What does it mean for an object to be in equilibrium?
An object is in equilibrium when there is no resultant force and no resultant torque about any point
What is meant by the center of gravity?
The center of gravity of an object is the point through which its entire weight appears to act.
Write down the equation for calculating a moment.
Moment = F × d
How do you determine equilibrium conditions for forces?
Ensure that: (1) The sum of all horizontal forces equals zero; (2) The sum of all vertical forces equals zero; (3) The sum of all moments about any pivot equals zero.
How do you calculate torque for a couple?
Torque = Force × Perpendicular distance between forces in the couple.
What should you include in free-body diagrams?
Represent all forces acting on an object as arrows with correct magnitudes and directions labeled clearly.
