Mechanics Flashcards
What’s the difference between a scalar and a vector.
A vector has magnitude and direction whereas scalar just has magnitude.
Some examples of vectors?
Vector = displacement (m), velocity (ms^-1), force (N), acceleration (ms^-2), weight (N), etc.
Some examples of scalars?
Scalar = distance (m), speed (ms^-1), mass(kg), temperature (K), volume (m^3), power (W), density (kgm^-3), time (s), energy (J), etc.
What does a free body diagram show?
A free body is the centre of mass of the object and what forces are acting on it.
What are the two conditions for a body in equilibrium?
- The resultant force in any direction must be 0.
- The resultant moment about any point must be 0.
Define the moment of a force.
Moment - force x perpendicular distance from the line of action of the force to the axis or point of rotation. M =Fx.
Define a couple.
A “couple” is a pair of equal and opposite forces acting on the same body, but along different lines of action. The moment of a couple is sometimes called “torque”. The torque of a couple is defined as, one of the forces x perpendicular distance between the lines of action of forces.
State the principal of moments.
The principal of moments states that for a body in equilibrium, the sum of the clockwise moments = sum of anticlockwise about any point.
Define “centre of mass”.
The “centre of mass” of an object is the point through which a single force has no turning effect, it is found in the centre of uniform object.
How to resolve forces on a slope?
- Label the forces acting on the object.
- Sketch a tip-to-tail diagram of the forces.
- Resolve the forces parallel and perpendicular to the slope.
O
B
O
B
What direction is the sin (theta)?
Vertical
What direction is the cos (theta)?
Horizontal
What are coplanar forces?
When all forces are acting in the same plane, they are called coplanar forces.
