P2.2 Forces Flashcards
What are forces measured in?
Newtons (N)
How would you show force on a diagram? (3)
The direction of the arrow shows the direction of the force
The length of the arrow is proportional to the size of the force
Arrows point outwards of the diagram
Name 5 forces
Upthrust (only in water) Drag Friction Weight Thrust
What’s the resultant force?
The overall force acting on an object
How do you work out the resultant force?
You minus the smaller force from the larger force
How much resultant force does a stationary object have?
Zeroooooo
Describe the resultant force of a moving object
At a constant speed it has no resultant force
Of its accelerating or decellerating then it has a resultant force
What’s acceleration measured in?
m/s squared
How’d you work out force?
Mass X acceleration
What’s the terminal velocity?
The maximum velocity that an object is able to achieve
What factors affect the terminal velocity?
The driving force that the object can generate
How streamlined the object is
The fluid the object is travelling through
What’s the gravitational field strength on earth?
10 N/kg
How do you calculate weight?
Mass X gravitational field strength
What’s the relationship between the force applied and the extension of a spring?
Directly proportional
What’s Hooke’s Law?
The extension of an object is directly proportional to the force that is applied to it provided that the limit of proportionality is not exceeded F = k X e F = force k = Spring constant e = extension
What’s the spring constant measured in?
N/m
The greater the force constant the _______ the material.
The force constant can be found by calculating the _________ ___ __ ________.
- Stiffer
2. Gradient of a force
Explain why a parachutist reaches a terminal velocity and why opening the parachute reduces the terminal velocity (6)
Just as the parachutist leaves the plane the only force acting in him is weight
Then the air resistance force increases and he carries in getting faster because the air resistance force is less than his weight
He reaches a terminal speed when the air resistance and weight force are balanced
Then when he opens the parachute the surface area increases and that increases the air resistance meaning the forces are unbalanced and the parachutist slows down
Finally the parachutist reaches another terminal velocity at the end of the jump when the forces balance again
