forces

• A normal force is exerted perpendicular to the surface an object rests on.
• when a force is a vector quantity, it has both magnitude and direction.
• when a force is a scalar quantity it only has magnitude and no direction
• types of vector quantities: force, velocity, displacement, acceleration, momentum, work, energy
• types of scalar quantities are distance, mass, time, temperature, speed, energy, power, and momentum
• distence (scalar) is the distance between two points on a line, measured in metres or kilometres
• displacement (vector) - the movement between its starting point and end point measured in a straight line
• contact forces are forces that act between two objects that are in contact with each other e.g. friction, air resistance, tension, and normal contact force
• non-contact forces are forces that do not involve the direct contact of two objects e.g. weight, magnetic force, gravitational force, electrostatic force
• newtons third law = for every action there is an equal and opposite reaction because forces are equal and opposite
• distence (m) = speed(m/s)x time(s) e.g s=v x t
• speed (scalar) is how fast you are going, velocity (vector) is speed in a given direction
• an object traveling in a circle's speed is constant, but its velocity is constantly changing as its direction is changing
• A force can change the shape of an object, or change its motion or its state of rest.
• Force is measured in Newtons, N.
• The equation used for momentum is Momentum = mass x velocity (kgm/s).
• An impact is the action of one object hitting another.
• These all reduce the force experienced because they increase the time that the force is experienced for.
• The equation which links force, momentum and time is F = ma, where F is force, m is mass and a is acceleration.
• Calculating the impact force involves dividing the change in momentum by the time it occurs for.
• Crumple zones are used for protection.
• The change in momentum happens over a larger time, therefore the person experiences less force.
• Entry, Descent, and Landing – often referred to as "EDL" – is the shortest and most intense phase of the Mars 2020 mission.
• To safely go from those speeds down to zero, in that short amount of time, while hitting a narrow target on the surface, requires “slamming on the brakes” in a very careful, creative and challenging way.
• Momentum is the product of mass and velocity.
• The equation for momentum is p = mv.
• Momentum is a conserved quantity in a closed system.
• The total momentum before an event in a closed system is equal to the total momentum after an event.
• Before a collision, the total momentum is equal to the total momentum after the collision.
• The total momentum in an explosion or collision stays the same.
• In an explosion or collision, the total momentum stays the same.
• The units for momentum, mass and velocity are known.
• Momentum can be calculated using the equation p = mv.
• Momentum can be rearranged and used in the equation p = mv.
• Knowing the units for momentum, mass and velocity is important for understanding how hard it is to stop a moving object.
• When two objects collide, the equation p = mv can be used to calculate the momentum.
• Momentum is a key concept in understanding how hard it is to stop a moving object.