Topic 15- Forces and Matter

Question 1

What is the difference between elastic distortion and inelastic distortion

Answer 1

• Elastic distortion the object returns to its original shape
• Inelastic distortion, too much force has been exerted, does not return tto original shape

Question 1

Why do elastic objects need more than one force to change shape?

Answer 1

-Only one force the would just move
-To bend/ extend/compress they need two forces
-Could be the earth (newtons third law)

Question 2

What is the equation for spring constant or linear elastic distortion?

Answer 2

Energy supplied = spring constant x extension

Question 3

How to calculate the work done?

Answer 3

Energy transfer= 1/2 spring constant x extension^2

Question 4

What is the letter format of the spring constant equation?

Answer 4

F= k x 𝑥

Question 5

What is the difference between linear and non-linear force and extension?

Answer 5

-after limit of proportionality, non-linear distortion occurs
-Inelastic distortion occurs

Question 6

Core Practical: Extension and work done on a spring?

Answer 6

• 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

Question 7

How to improve this experiment?

Answer 7

-Heavier/lighter mass
-Less stiff or more stiff spring

Question 8

Why does atmospheric pressure change?

Answer 8

-Higher up there are less molecules above, meaning less pressure

Question 9

What is the pressure in a fluid?

Answer 9

The pressure of the fluid above it and the atmospheric pressure

Question 10

What is the equation for pressure?

Answer 10

Pressure= Force/ Area

Question 11

How does pressure increase in fluids?

Answer 11

• In a more dense fluid
• Deeper in a fluid

Question 12

What is the equation for pressure involving depth/ 3d?

Answer 12

Pressure = Density x Gravity x Height/depth

Question 13

What is pressure measured in?

Answer 13

Pascals

Question 14

What force happens on objects in a fluid?

Answer 14

Upthrust

Question 15

Why does upthrust occur?

Answer 15

-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

Question 16

Why do objects only move up and not sideways in fluid?

Answer 16

-Same depth there is the same pressure
-Balanced forces on both sides

Question 17

When does an object float above the water?

Answer 17

When it is less dense than the water

Question 18

When does an object partially float?

Answer 18

Needs to displace a bit of water in order to get to a level with sufficient upthrust to balance its weight.

Question 19

When is an object fully submerged in the fluid?

Answer 19

• 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

Question 20

When does an object fully sink?

Answer 20

-more dense than the water
-Weight is always greater than the upthrust

Question 21

What does the displaced fluid equal?

Answer 21

The upthrust.

Question 22

How can we find the displaced fluid?

Answer 22

Eureka can

Question 23

What is Boyles law?

Answer 23

That at a constant temperature, pressure is inversely proportional to volume