Forces

• What does a scalar quantity have? A magnitude but no direction
• What does a vector quantity have? A magnitude and direction
• How are arrows used to represent vector quantities? - Length of the arrow shows the magnitude - Arrow points in the direction that the vector quantity is acting
• What are forces? Vector quantities
• How does a force occur? When two or more objects interact
• What will forces either be? [2] - Contact forces - Non-contant forces
• What are contact forces? Objects are touching
• What are non-contact forces? Objects are not touching
• What are some examples of scalar quantaties? [6] - Time - Mass - Temperature - Speed - Distance - Thermal Energy
• What are examples of vector quantities? [4] - Weight - Velocity - Force - Displacement
• What is gravity? The force of attraction between all masses
• Why is the force of gravity close to Earth? Due to the gravitational field around the planet
• What is the mass of an object related to? The amount of matter it contains and is constant
• What is weight? The force acting on an object due to gravity
• What does a weight of an object depend on? [2] - Gravitational field strength of where the object is - And if it is directly proportional to its mass
• What is weight as a force measured in? Newtons
• What equipment is used to measure weight? [2] - Calibrated spring balance - Newtonmeter
• How is mass measured? In kilogram with a mass balance because it is not a force
• How do you calculate the weight of an object? Weight (N) = Mass (Kg) x Gravitational field strength (N/Kg) W=mg
• What is the gravitational field strength for Earth? 9.8 N/Kg
• What is the gravitational field strength on the Moon? 1.6 N/Kg
• What happens to the weight if you increase the mass of the an object? It increases
• Is the weight and mass of an object directly proportional? Yes
• What can a free body diagram be used to show? Different forces acting on an object
• What are scale vector diagrams used to illustrate? The overall effect when more than one force acts on an object
• Where else can scale vector diagrams be also used? When a force is acting in a diagonal direction
• What happens when a force causes an object to move? Work is done on the object
• Why is work done on an object, when a force causes it to move? Because it requires energy to move the object
• When is one joule of work done? When a force of one newton causes a displacement of one metre: 1 joule = 1 newton metre
• What is the equation for work done? Work done (J) = Force (N) x Distance (m) W=fs
• What happens when work is done? Energy transfers take place within the system
• What happens when work is done to overcome friction? Causes an increase in heat energy
• How do you change the shape of an object? By applying more than one force
• What is elastically deformed? When the object returns to its original shape after the forces are removed
• What is inelastically deformed? If the object does not return to its original shape
• What is the extension of an elastic object directly proportional to? The applied force
• What happens once the limit of proportionality has been exceeded? [3] - Doubling the force will no longer double the extension - Relationship becomes non-linear - A force-extension graph will stop being a straight line
• What equation applies to the linear section of a force-extension? Force (N) = Spring constant (N/m) x Extension (m) F=ke
• What does the spring constant indicate? How easy it is to stretch or compress a spring
• What happens if the spring constant is high? Stiffer the spring