Mechanics Flashcards
Particle
The mass can be assumed to be concentrated on a certain point so the weight acts at a point
Rod
- The mass can be considered to be distributed along a straight line.
- Doesn’t bend
Lamina
The mass can be considered to be distributed across a flat surface
Uniform body
Mass is evenly distributed over its entire volume. The weight can be considered to act at a single point in the middle
Light
No mass
Inextensible string
Doesn’t stretch under a load
Smooth surface
Ignore frictional forces
Rough surface
Consider friction
Smooth and light pulley
Pulley has no friction or mass
Why is the tension the same in a pulley
-Pulley is smooth
Why is the acceleration the same in a pulley
-The string is inextensible
Comment on the assumption that the resistive force remains constant:
(i) in the case when the cyclist is accelerating,
unlikely as an increase in speed will cause increase in air resistance
Comment on the assumption that the resistive force remains constant:
(ii) in the case when she is maintaining a steady speed.
more reasonable as speed is constant
Making reference to the mass of the ball and the force it experiences, explain why it is
reasonable to assume that the acceleration is constant.
mass of ball remains constant, force is constant
F = ma so a constant
