Forces Flashcards
What happens when a force acts on an object?
it can cause the object to speed up, slow down, change direction or change shape.
Is force a vector quantity?
force is a vector quantity because it has direction.
What is gravitational force?
Gravitational force acts between two masses such as the Moon and the Earth.
What is an electrostatic force?
An electrostatic force acts between two charges such as when you rub a balloon and place it near someone’s hair
What is friction?
Friction is a force that occurs when two objects are in contact with each other and opposes motion. The more friction the larger the driving force needed to achieve the same speed.
What is Isaac Newtons first law?
When forces acting on an object are unbalanced, there will be a resultant force which will cause the speed of the object to change in the direction of the resultant force.
When the forces acting on an object are balanced, there is no resultant force so there will be no change to the speed of the object. If the object is a travelling at a certain speed, it will continue to do so at the same speed. If the object is stationary, it will remain stationary.
What is weight?
Weight is the force exerted on an object by gravity and is measured in Newtons.
What is the Earth’s gravitational field strength?
The Earth’s gravitational field strength is 10 N/kg.
What does the Earth’s gravitational field strength of 10 N/kg mean?
It means that for each kilogram of an object’s mass, there is 10 N of force acting on it.
What is the difference between weight and mass?
Mass is constant, while weight changes depending on gravity.
How are weight and mass related?
Weight and mass are directly proportional. If the mass of an object doubles, its weight will also double, providing the gravitational field strength is constant.
What is the centre of gravity of an object?
where weight of an object acts at the point of the object
Can the centre of mass be inside or outside of an object?
either depending on its shape
What happens when an object is suspended from a string?
it will come to rest with its centre of gravity immediately below the point of suspension
What factors influence the distance travelled when coming to a stop?
The distance travelled when coming to a stop depends on several factors which influence both the reaction time of the driver (thinking distance) and friction between the tyres and the road (braking distance).
How do higher speeds affect thinking and braking distance?
Higher speeds will increase both thinking distance and braking distance since the car will travel a larger distance in the same time that it takes to come to a stop.
How does increasing the mass of the car affect braking distance?
Increasing the mass of the car will increase the braking distance (but not the thinking distance).
Why does increasing the mass of the car increase the braking distance?
This makes sense if we use the equation: force = mass x acceleration. Acceleration refers to the car coming to a stop, and will have a negative value since we are slowing down. If we double the mass of the car, the force needed to bring the car to a stop will also double to achieve the same rate of deceleration.
What are the two main forces acting on falling objects?
the force of gravity pulling them towards Earth and air resistance acting in the other direction slowing their fall.
How do the forces acting on a falling object change as it falls?
The size of these forces change as the object falls until it reaches a constant speed called terminal velocity.
