Mechanics Flashcards
What are Newton’s Three laws?
- An object will stay in constant motion or stationary unless it is acted upon by a resultant force.
- Force is directly proportional to acceleration and mass when the other is constant.
- Every force has an equal and opposite reaction forces.
What orientation should the forces be to the plane when the plane is inclined?
The forces should be parallel or perpendicular to the inclined plane
What should you do to weight when the object is on an inclined plane?
You should use the angle of the plane to find the forces parallel and perpendicular to the plane.
What effect does a parallel force to a plane have on a perpendicular force to a plane?
None.
What is a moment and how do you calculate it?
A moment is a forces which measures the objects tendency to rotate about a fixed pivot.
You calculate a moment by:
Moment = Force x the perpendicular distance to the Force’s line of action
What are the gradients of a distance-time graph, a displacement-time graph and a velocity-time graph
Distance-time gradient is speed
Displacement-time gradient is velocity
Velocity-time graph is acceleration
What is the horizontal acceleration on an object when it has been projected?
None as air resistance is negligible. If air resistance wasn’t negligible, the object would not be able to fly as far and would reach its maximum height closer to its projection point than if there wasn’t air resistance.
How do you find the Tension in a pully?
You resolve on only one of the objects using F = ma
How do you find the acceleration or force of a car pulling a trailer?
You would resolve as a whole system as this would remove the tension in the tow bar as it would be going in both directions, cancelling itself out.
How do you calculate momentum?
Momentum = velocity * mass
What is a change in momentum called?
Impulse measured in Kgm/s or N/s
What is the area under an force-time graph?
Impulse measured in N/s
What two types of collisions can occur and what is conserved in each of them?
Elastic collision - total kinetic energy is conserved and total momentum is conserved
Inelastic collision - momentum is conserved but kinetic energy isn’t conserved as some will be lost as internal energy transferred through friction.
What velocity should you use to calculate its momentum when an object is rebounding off a wall at an angle?
You should use the velocity perpendicular to the wall (along the wall’s normal).
How would you calculate the velocity of 2 objects that have collided and then stuck together after the collision?
You would treat them as one particle and add their mass together. You would then use the total momentum of both particles and divide that by their combined mass to find their velocity.
