Chapter 4: Dynamics Flashcards
Define mass
It is the property of a body which resists change in motion
Define momentum
It is the product of the mass of a body and its velocity
Define inertia
It is the tendency of a body to stay in a state of rest or uniform motion
Define force
It is a push or pull that can cause a change in momentum to a body when acting on it
State Newton’s First Law
In the absence of a resultant force, a body at rest stays at rest while a body in motion continues its motion at uniform speed
State Newton’s Second Law
The rate of change of momentum is proportional to the resultant force acting on a body, and the momentum changes in the direction of the resultant force
Define impulse
It is the product of the average force exerted and the average time which it acts
Additional info:
Impulse = Change in momentum
State the 3 car safety features and how they prevent damage/injury
- Front and rear crumple zones (Structure of the car will not give way during a collision as it increases the amount of time of the car to stop, reducing the resultant force exerted on the car)
- Seatbelts (prevent people from being thrown around in a car, and stretches during a crash to increase the time it takes for the person to stop moving)
State the 3 car safety features and how they prevent damage/injury
- Front and rear crumple zones (Structure of the car will not give way during a collision as it increases the amount of time of the car to stop, reducing the resultant force exerted on the car)
- Seatbelts (prevent people from being thrown around in a car, and stretches during a crash to increase the time it takes for the person to stop moving)
- Airbags (Prevent people from colliding with hard objects and increases the time taken for the person to stop moving)
State Newton’s Third Law
When Body A exerts a force on Body B, Body B exerts a force of equal magnitude but opposite direction on Body A
Define weight
It is the gravitational force exerted on an object by the Earth
Define apparent weight
It is the force exerted on an object by the body that is freely supporting it
When does weightlessness occur
When apparent weight = 0N
State the Principle of Conservation of Linear Momentum
The total momentum in a system remains constant unless an external force acts on the system
State the properties of these 3 collisions:
1. Elastic collision
2. Completely Inelastic collision
3. Superelastic collision
- KE(i) = KE(f), RSA = RSS
- v of both bodies are equal (bodies coalesce as some KE is converted to potential/internal energy due to deformation)
- KE(i) < KF(f)`
