KHP 415 FINAL EXAM

The perpendicular distance b/w the line of force and the axis defines what?

1. none of the choices are correct

2. moment arm

3. fulcrum

4. torque

2

Which of the following is a characteristic of torque?

1. It is characterized by magnitude

2. it is a vector quantity

3. all of the choices are characteristics of torque

4. it is characterized by direction

3

In the human body, most of the lever systems formed by muscles pulling on bones are what class?

1. 3rd class

2. no particular class is dominant

3. 1st class

4. 2nd class

1

Torque is the angular analogue of what?

1. impulse

2. momentum

3. force

4. mass

3

A 30 kg child sits on the right end of a see-saw 1 m from the axis. If a 20 kg child sits on the left end of the see-saw 2 m from the axis, what will happen?

1. the see-saw will tilt to the left

2. the see-saw will tilt to the right

3. the see-saw will balance

4. need more information to predict outcome

1

The resistance arm (RA) will always be longer than the force arm (FA) in what class lever?

1. 1^st class

2. 3^rd class

3. none of the classes are correct

4. 2^nd class

2

Third class lever systems favor which of the following?

1. all of the choices are correct

2. speed

3. range of motion

4. strength

5. both speed and range of motion

5

A seesaw is an example of which class of lever?

1. 1^st class

2. not a lever

3. 2^nd class

4. 3^rd class

1

The relative efficiency of a lever is proportional to which of the following?

1. length of the force arm

2. the amount of force needed to move the lever

3. length of the resistance arm

4. mechanical advantage of the lever

4

When a muscle contracts at a joint, which of the following affects torque?

1. the stabilizing component of muscle force

2. none of the choices affect torque

3. the dislocating component of muscle force

4. the rotary component of muscle force

4

The amount of torque which must by generated by the biceps brachii at the elbow in order to maintain the arm in a particular position is 50 Nm. If the biceps attaches to the radius at a perpendicular distance of 3 cm from the joint center at the elbow, how much force must the muscle produce?

1. 1.5 N

2. 1667 N

3. 17 N

4. 150 N

2

Which of the following affects the force-generating capability of a muscle?

1. all of the choices affect the force-generating capability of a muscle

2. the angle and distance from the joint center of the tendon attachment to bone

3. the velocity of muscle shortening

4. the muscle length and cross-sectional area

1

Which of the following must be true for an object to be in a state of static equilibrium?

1. all of the choices must be true

2. the sum of all horizontal forces acting on the object must be equal to zero

3. the sum of all vertical forces acting on the object must be equal to zero

4. the sum of all torques acting on the object must be equal to zero

1

Which of the following does not increase stability?

1. lower the COG

2. decrease mass

3. increase size of base of support

4. increase friction

2

Which of the following will benefit mobility?

1. increase friction

2. raise center of gravity

3. increase base of support

4. increase mass

2

Which of the following quantities is zero for an object in static equilibrium?

1. neither A nor B

2. momentum

3. kinetic energy

4. both momentum and kinetic energy

4

In which of the following situations is maximal stability desirable?

1. maximal stability is desirable in neither situation

2. a Sumo wrestler's crouched defensive stance

3. a swimmer's starting position on the blocks before a race

4. maximal stability is desirable in both situations

2

Which statement is true regarding moment arm?

1. For torque to remain constant, more force must be produced when moment arm decreases.

2. Both that the moment arm is largest when the angle of pull on a bone is 90° and that changes in moment arm directly affect joint muscle torque

3. Moment arm is largest when the angle of pull on a bone is 90°.

4. all of the statements are true regarding moment arm.

5. Changes in moment arm directly affect joint muscle torque.

4

Which of the following statement regarding mechanical advantage (MA) is true?

1. MA is always less than 1 in class III level

2. all of the statements are true

3. MA is always larger than 1 in class II lever & MA is always less than 1 in class III level

4. MA is always larger than 1 in class II lever

5. MA is always equal to 1 in class I lever

3

What will happen to the COM of a human body if the arms are raised up overhead?

1. it will not change

2. need more information to predict

3. it will move up

4. it will move down

3