Forces

Question 1

what is a helical spring

Answer 1

the extension of the spring is directly proportional to the load (force applied)

Question 2

what is the limit of proportionality

Answer 2

the point at which a spring stops obeying Hooke’s law

Question 3

what is hookes law

Answer 3

the extension is directly proportional to the force applied

Question 4

the is the equation of a spring constant

Answer 4

F = kx (k is the spring constant

Question 5

what is the difference between elastic stretching and plastic stretching

Answer 5

-Elastic stretching will return to its original length
-plastic stretching will not return to its original length, it is permanently deformed

Question 6

what is newtons first law

Answer 6

an object at rest will remain at rest, and an object in motion will remain in motion at the same speed unless acted on by a force

Question 7

what is newtons second law

Answer 7

when there is a force acting on an object, it will accelerate with acceleration directly proportional to the force

Question 8

what is newtons third law

Answer 8

every reaction has an equal and opposite reaction

Question 9

equation for acceleration

Answer 9

a = (v-u)/t

Question 10

equation for Force

Answer 10

F = ma

Question 11

what is resultant force

Answer 11

the sum of all the forces acting on a body

Question 12

what is terminal veolicty

Answer 12

-when gravity becomes equal to air resistance

Question 13

what does air resistance depend on

Answer 13

-speed relative to air
-size/shape of the object

Question 14

what is the maximum acceleration of an object if it is dropped on earth

Answer 14

10m/s squared

Question 15

explain a graph question of terminal velocity (5 marks) memorise

Answer 15

-there is a resultant force
-it accelerates
-air resistance and friction increases as speed increases
-so acceleration decreases
-eventually air resistance + friction = driving force (forces are balanced)
-hence resultant force is zero
-object travels at a constant speed (terminal velocity)

Question 16

what are vectors and scalars

Answer 16

vectors - magnitude and direction
scalars - magnitude only

Question 17

practical to investigate how extension varies with applied force for helical springs, metal wires and rubber bands

Answer 17

1. Set up your apparatus as shown in the
2. Measure the length of your spring without
   any hanging masses.
3. Hang a mass of 100g on the spring
4. Measure the new length of the spring
5. Calculate the extension of the spring
6. Repeat steps 3-5 for increasing the mass
   in increments of 100g
7. Take note of your results in the table.