Topic 15- Forces and Matter Flashcards
What is the difference between elastic distortion and inelastic distortion
- Elastic distortion the object returns to its original shape
- Inelastic distortion, too much force has been exerted, does not return tto original shape
Why do elastic objects need more than one force to change shape?
-Only one force the would just move
-To bend/ extend/compress they need two forces
-Could be the earth (newtons third law)
What is the equation for spring constant or linear elastic distortion?
Energy supplied = spring constant x extension
How to calculate the work done?
Energy transfer= 1/2 spring constant x extension^2
What is the letter format of the spring constant equation?
F= k x 𝑥
What is the difference between linear and non-linear force and extension?
-after limit of proportionality, non-linear distortion occurs
-Inelastic distortion occurs
Core Practical: Extension and work done on a spring?
- Clamp stand with a spring on it
- Measure length of spring
-Add mass, measure new length x 5
-Convert mass to kg
-Use weight= gravity x mass for weight
-Find extension in metre - Plot graph
- use spring constant = force/ extention
How to improve this experiment?
-Heavier/lighter mass
-Less stiff or more stiff spring
Why does atmospheric pressure change?
-Higher up there are less molecules above, meaning less pressure
What is the pressure in a fluid?
The pressure of the fluid above it and the atmospheric pressure
What is the equation for pressure?
Pressure= Force/ Area
How does pressure increase in fluids?
- In a more dense fluid
- Deeper in a fluid
What is the equation for pressure involving depth/ 3d?
Pressure = Density x Gravity x Height/depth
What is pressure measured in?
Pascals
What force happens on objects in a fluid?
Upthrust
Why does upthrust occur?
-More pressure in deeper water means force is greater at a lower depth
- This force is more than the weight of the object
- Will stop moving when both forces are balanced
Why do objects only move up and not sideways in fluid?
-Same depth there is the same pressure
-Balanced forces on both sides
When does an object float above the water?
When it is less dense than the water
When does an object partially float?
Needs to displace a bit of water in order to get to a level with sufficient upthrust to balance its weight.
When is an object fully submerged in the fluid?
- same density as the water
- When it needs to displace the same amount of water as its volume to have enough upthrust to balance its weight
When does an object fully sink?
-more dense than the water
-Weight is always greater than the upthrust
What does the displaced fluid equal?
The upthrust.
How can we find the displaced fluid?
Eureka can
What is Boyles law?
That at a constant temperature, pressure is inversely proportional to volume
