forces and matter

Question 1

explain that stretching, bending or compressing and object requires more than one force

Answer 1

• need more than one force
  -> otherwise the object would move in direction of the applied force
  ex spring returns to original shape

Question 2

what is elastic distortion

Answer 2

it can go back to original shape and length after the force has been removed

Question 3

what is inelastic distortion

Answer 3

does not return to its original shape and length after the force has been removed

Question 4

the equation for linear elastic distortion including calculating the spring constant =

Answer 4

force exerted on spring (N) = spring constant (N/m) * extension (m)

F = k * x

Question 5

use the equation for linear elastic distortion (with spring constant) to CALCULATE WORK DONE IS STRETCHING A SPRING

Answer 5

energy transferred in stretching (J) = 0.5 * spring constant (N/m) * extension squared (m squared)

E = 0.5 * k * x squared

Question 6

what is linear relationship between force and extension

Answer 6

• extension of an elastic object is DIRECTLY PROPORTIONAL to the force applied
• on a graph it would = a straight line

Question 7

what is a non - linear relationship between force and extension

Answer 7

• when extension is no longer proportional to force
• the object stretches more for each unit of increased force

Question 8

where is the limit of proportionality on a non linear graph

Answer 8

• when object stretches more to increase in unit of force

Question 9

where is the elastic limit on a non linear graph

Answer 9

• where the object is permanently stretched

Question 10

core practical: investigate the extension and work done when applying forces to a spring

Answer 10

1. measure NATURAL LENGTH OF SPRING(no load applied)
   with a MM ruler clamped to a stand
2. take reading at EYE LEVEL and allow spring to come to REST
3. RECORD the mass and measure new length of spring
   (extension is change in length)
4. REPEAT until have enough measurements (ex no fewer than 6)
5. PLOT a force extension graph of results
6. will start to curve if you exceed the limit of proportionality

Question 11

core practical: investigate the extension and work done when applying forces to a spring. EQUIPMENT

Answer 11

• fixed ruler
• clamp
• wighted stand
• hanging mass
• extra masses
• spring

Question 12

core practical: investigate the extension and work done
when applying forces to a spring. PILOT EXPERMINET

Answer 12

• SHOWS WHAT SIZE MASSES TO USE
  1. use IDENTICAL SPRING and LOAD with MASSES one at a time and record the FORCE (WEIGTH) and EXTENSION each time
  2. plot force - extension graph to get a STRAIGTH LINE for at least first 6 points
  3. if it curves TOO EARLY => use SMALLER MASSES

Question 13

core practical: investigate the extension and work done when applying forces to a spring . what your graph tells you/ should find on the graph

Answer 13

1. larger force = bigger extension
   -> more work done to cause larger extension
2. find the work done for particular force by calculating area under linear section or force - extension graph up to that value of force

Question 14

core practical: investigate the extension and work done when applying forces to a spring. what is the force for elastic distortions (graph)

Answer 14

gravitational force which is equal to F = kx

Question 15

what is the limit of proportionality on a non linear graph

Answer 15

• where the object stretches more for each unit of increase in force