Biomechanics MCQs - MCQtimes.com

Biomechanics

Use the equation P = F ÷ A to determine the pressure on the knee joint (area = 100 cm²) when a 70 kg person is standing on one leg (assume that 70 kg is the body mass above the knee). Hint: convert cm² to m²:

7 kPa

70 kPa

700 kPa

7000 kPa

Using P = F ÷ A and remembering that the weight, F, of a person with mass 70 kg is 70 × 10 and converting 100 cm²–0.001m², putting in the numbers gives:
P = 70 × 10 ÷ 0.001 = 700,000 Pa = 700 kPa.

Author: rikazzz Comment

Biomechanics

A person whose mass is 50 kg would have a weight closest to:

50 kg because mass and weight are directly proportional to each other (on Earth)

50 N because F1 = -F2 (Newton’s third law)

500 kg because weight = mass × 10 (approximately)

500 N because F = m × a (Newton’s second law)

Choice C is almost correct, but the unit of force is the newton, while the kilogram is the unit of mass.

Author: rikazzz Comment

Biomechanics

What is a nurse attempting to minimise by getting close to a patient during a manual handling procedure?

The load arm

The size of the fulcrum

The effort arm

The patient’s weight

The shorter is the load arm, the smaller is the muscular effort that is required to move the lever and load.

Author: rikazzz Comment

Biomechanics

Fixed traction may be applied by a device such as a “Thomas splint”. In this case, the counter-traction force is supplied by:

The push of the appliance on a fixed point on the body (such as the ischial tuberosity)

An adhesive bandage wrapped around the lower leg

The pull of a wire that is made taut by turning a wingnut attached to the patient’s foot

The weight of the patient’s leg and the friction between the patient and the bed

Fixed traction does not involve cords and hanging masses. The Thomas splint involves “stretching” the leg between the foot and the pelvis.

Author: rikazzz Comment

Biomechanics

The magnitude of the traction force in a Hamilton-Russell traction is determined by;

The vector addition of the forces in the cords

The hanging mass multiplied by 9.8

The component of the patient’s weight that is perpendicular to the bed

The number of pulleys in the system

The moveable pulley allows the one cord to exert more than one force on the leg. So the magnitude of the force is determined by adding the forces vectorially.

Author: rikazzz Comment

Biomechanics

Good manual handling technique on an unconscious patient involves which of the following?

Using the muscles of the arms

Instructing the patient on how to shift themself

Using the muscles of the legs

Using the muscles of the back

The leg muscles are the largest (and therefore the strongest) in the body. An unconscious patient cannot take instruction.

Author: rikazzz Comment

Biomechanics

What is the aim of “correct lifting technique”? To:

Maintain balance by keeping the centre of gravity over the base of support.

Avoid working with heavy loads that are on the ground.

Use the bones and muscles of the leg.

Keep the back straight while using it as a lever.

The leg bones and muscles are the strongest in the body so are most suited to coping with large forces.

Author: rikazzz Comment

Biomechanics

One of the following statements is WRONG. Which one?

A patient’s inertia may be decreased by using several people to assist in their transfer.

The position of a person’s centre of gravity may be altered by altering the position of their arms and legs.

Base of support may be increased by adopting a wide stance with your feet.

Friction between a patient and the bed may be reduced by using a slide sheet.

Inertia is a fixed attribute of an object that cannot be changed without changing its mass.

Author: rikazzz Comment

Biomechanics

In straight leg traction (Buck’s extension), the force of counter-traction is supplied by friction (between the patient and the bed) and also by:

The component of the patient’s weight that is perpendicular to the bed

The component of the patient’s weight that is parallel to the bed

Gravity acting on the hanging mass

Using cords to attach the patient to the head of the bed

The bed is tilted head down so that patient is tending to side away from the traction mass.

Author: rikazzz Comment

Biomechanics

Consider the action of moving from having both feet flat on the ground to standing on “tiptoes”. Which of the following correctly identifies the fulcrum, the load force, the effort force and the lever?

Fulcrum is the heel, load is the body’s weight, effort is the pull of the ham-strings and lever is the tarsal bones of the foot.

Fulcrum is the ball of the foot, load is the body’s weight, effort is the pull of the calf muscles and lever is the tarsal and metatarsal bones of the foot.

Fulcrum is the ankle, load is the weight of the foot, effort is the pull of the hamstrings and lever is the tibia and fibula bones.

Fulcrum is the knee, load is the weight of the foot, effort is the pull of the calf muscles and lever is the tibia and fibula bones.

Fulcrum has to be the “ball” of the foot (the rounded area superficial to the joint between metatarsal and proximal phalanx of the hallux), and load must be the weight of the body.

Author: rikazzz Comment