Biomechanics
In cars, the aim of safety features, such as seatbelts, padding on the dashboard, collapsible steering columns, airbags and body panels that crumple progressively, is to minimise the unbalanced force on occupants during a crash. Bearing Newton’s second law in mind, how do such features achieve this? They:
Minimise the occupant’s deceleration.
Maximise the occupant’s deceleration.
Prevent whiplash injuries.
Convert an unbalanced force into a net force.
Minimise the occupant’s deceleration.
Say the occupant has a mass of “m”. Newton’s second law states F = m ร a to make the unbalanced force F as small as possible, and then the acceleration “a” must be made small. Acceleration may be positive or negative; the latter is often called a “deceleration”.
Minimise the occupant’s deceleration. Say the occupant has a mass of “m”. Newton’s second law states F = m ร a to make the unbalanced force F as small as possible, and then the acceleration “a” must be made small. Acceleration may be positive or negative; the latter is often called a “deceleration”.
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When two forces of magnitude 6 N and 10 N are added vectorially, what value could the resulting vector NOT have?A. 4 N
B. 6 N
C. 10 N
D. 18 N
Which of the following is not an example of a force?
A. Tension
B. Friction
C. Inertia
D. Weight
What is the purpose of using a slide sheet in patient manual handling?
A. To extend the patient’s base of support
B. To facilitate raising the patient’s centre of gravity
C. To minimise friction between the patient and the bed
D. To minimise the patient’s inertia
Traction forces may be represented by vectors. In Hamilton-Russell traction, which of the following vectors is equal in magnitude to the traction force?
A. The component of the patient’s weight that is perpendicular to the bed
B. The component of the patient’s weight that is parallel to the bed
C. The vector in A subtracted from the patient’s weight
D. The resulting vector when the vectors in A and B are added
What does the term “friction” refer to?
A. The tension force generated when a muscle contracts
B. A force that acts in the opposite direction to a motion
C. The resistance force that is overcome by an effort force
D. The force of gravity that causes an object to fall
When the biceps brachii muscle flexes the forearm, what is the forearm an example of?
A. A first-class lever
B. A second-class lever
C. A third-class lever
D. An efficient lever
Third-class lever systems are always inefficient for which one of the following reasons?
A. The effort arm is longer than the load arm.
B. The effort force required is less than the load force.
C. The fulcrum lies between the effort and the load. The load arm is longer than the effort arm.
D.
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