Forces Flashcards
What is the difference between a scalar and a vector quantity?
Scalar quantities have magnitude only, whereas vector quantities have magnitude and an associated direction.
What is the difference between a contact and non-contact force?
Contact forces physically touch objects, whereas non-contact forces are physically separated from objects.
What is momentum?
It is constant when travelling in a straight line at a constant speed, but changes due to a changing velocity. A resultant force must be acting on the object for the momentum to change.
What is meant by ‘resultant force’?
The remaining forces, when forced in all directions, have cancelled each other out.
What is the difference between mass and weight?
Weight is the force on a mass due to a gravitational field, whereas mass is the amount of matter an object has or how difficult it is to change an object’s velocity.
What is the relationship between extention and force applied?
Extention is directly proportional to the force applied (up to the limit of porportionality).
What are objects’ motions when subjected to forces?
When the resultant force is zero, the object does not accelerate, meaning it continues at a constant velocity (it could be stationary). When the resultant force is not zero, the object is either speeding up, slowing down, and/or changing direction.
How is work done against gravity?
An object’s height will increase, meaning its gravitational potential energy will increase.
How is work done against friction?
When work is done against friction, the temperature of the object rises; its thermal energy will increase.
When do springs behave elastically?
When the force exerted on it is directly proportional to its extension, the object returns to its original length when the force is removed, so it has not exceeded the limit of proportionality, and it deforms elastically.
When do spring not behave elastically?
When the force exerted on it is not directly proportional to its extension, meaning the object does not return to its original length, so when the force is removed, it has exceeded the limit of proportionality and it deforms inelastically.
What is an object’s centre of mass?
The point where the entire mass of an object or system of objects can be considered to be concentrated, simplifying the analysis of its motion and behaviour.
What is the relationship between joules and newtons per meter?
One newton-meter is equal to one joule.
