Biomech Unit 1 Part 2

Question 1

Define pressure

Answer 1

Pressure is the force exerted per unit area

Question 2

Unit for pressure

Answer 2

Pascal (N/m2)

Question 3

Define moment

Answer 3

tendency of a force to produce a rotation about an axis

Question 4

Another name for moment

Answer 4

torque

Question 5

SI unit for momeny

Answer 5

Nm

Question 6

Equation of moment

Answer 6

Moment = force x moment arm (distance from pivot)

Question 7

Second condition of static equilibrium? and fancy name

Answer 7

Sum of all the external moments acting on body must be zero –> rotational equilibrium

Question 8

What is a lever

Answer 8

rigid bar that pivots about a fulcrum –> aced on by an effort force and a resistance force

Question 9

Example of a lever in body

Answer 9

Muscles - effort force

try move or prevent move of a limb (rigid bar) by overcoming external forces (resistance) eg gravity

Question 10

Two purposes of lever system

Answer 10

amplify the effort force

amplify the distance moved thorugh

Question 11

Effort arm > resistance arm ?

Answer 11

magitude of effort force required to overcome is smaller that resistance –> mechanical advantage

Question 12

Resistance arm> effort arm?

Answer 12

resisance may be moved through a large disance. Mechanical disadvantage

Question 13

Effort arm/resistance arm = ?

Answer 13

mechanical advantage - >1 adv

Question 14

Muscles mostly work at mechanical advantage

Answer 14

FALSE - disadvantage as they are inserted close to the joint centre often

Question 15

Why disadvantage is useful

Answer 15

The force needed is larger but a greater distance of the resistance load is acheived therefore in the body a smaller change in muscle length will produce a greater movement of limb being moved. it is also quicker

Question 16

Define a first class lever and example

Answer 16

Fulcrum between effrot and resistance eg crowbar, scissors, see saw

Question 17

First class lever: mechanical adv or dis?

Answer 17

either depending on the arms

Question 18

Second class has a longer resistance arm than effort arm? also example

Answer 18

FALSE it has a longer effort arm

eg wheelbarrow

Question 19

Second class lever: adv or dis

Answer 19

ALWAYS works at advantage

(this allows a smaller effort force required)

Question 20

Define third class lever and example

Answer 20

effort located between the fulcrum and resistance. EG fishing rod, tweezers

Question 21

Third class: adv or dis?

Answer 21

ALWAYS disadvantage which allows it to move resistance a greater distance

Question 22

which lever is most common in body

Answer 22

third