Biomechanics final true/false questions
T/F: since force is a vector, it only has a magnitude
False; it has a direction too
T/F: As long as the distance between your center of mass and the earth's center of mass is constant, so is gravity
True
T/F: Assuming your mass is constant when you sleep, you can decrease pressure by lying on your back versus your side
True
T/F: The center of pressure under your left foot when standing may be in location of zero pressure
True
T/F: When a force vector is resolved into its orthogonal components, the magnitude of the resultant vector is always larger than any of the components
True
T/F: You performed vertical jumps on a force platform two times. The time you generate greater vertical impulse was the time you jumped higher
True
(T/F) A shuffleboard puck slows down as it slides on the floor because of its mass
false
A force couple produces only rotation without translation because the two torques act in the same direction.
false
A pole vaulter in flight has only kinetic energy
false
A torque and a moment of force do not have the same meaning.
false
By convention, clockwise torques are considered to be positive.
false
During the stance phase of running, positive power at the hip, knee, and ankle joints indicates eccentric contractions.
false
If mechanical work = zero, we can assume that the muscle contraction is eccentric
false
Moment of inertia about an axis always passes through the center of mass of a segment.
false
Only forces are shown in a free body diagram.
false
Person A, who has half the mass of Person B, will be able to cause the same impulse on an object as Person B if she moves with twice the velocity of Person B.
false
Potential energy is proportional to an object's mass and inversely proportional to its height from the ground.
false
Resistance of a thigh to rotate about its longitudinal axis is greater than its resistance to rotate about a mediolateral axis.
false
Second-class levers require large effort forces relative to resistant forces and maximize the speed of movement.
false
T/F: Backspin imparted on a golf ball is an example of the Magnus effect, in which low pressure on the bottom and high pressure on the top result in the ball lifting upward
false
T/F: Frictional force depends on the contact area, and the coefficient of friction between the two objects of interest
false
T/F: The normal force is always directed anteroposteriorly
false
The center of mass and the center of gravity are the same.
false
The direction of the torque vector changes if the force vector rotates around the axis of rotation.
false
The final acceleration in the golf club during the downswing is attributed to the moment of inertia decreasing as the club center of mass gets closer to the axis of rotation.
false
The largest moment of inertia of a segment is the one that passes through the center of mass.
false
The sum of torques about the center of mass of an object always equals zero
false
The total energy in a system can be created but not destroyed
false
To work your deltoids more during a lateral arm raise, bend your elbows slightly, bringing the weight closer to your trunk.
false
concurrent forces do not coincide at the same point
false
the strongest lever is a third class lever
false
You multiply joint moment with segment velocity to get joint power
false (this was ch 12 #14 he said he would change it to this bc original does not make sense)
T/F: During walking, the magnitude of GRF from highest to lowest is vertical, mediolateral, and anteroposterior
false; it is from high to low: vertical, anteroposterior, then mediolateral
T/F: an objects mass is not a good estimate of its inertia
false; they are related
A dynamic analysis is always conducted from the most proximal joint to the most distal joint.
true
A force has to be applied over some time interval for an impulse to be generated
true
A force has to be applied over some time interval for an impulse to be generated.
true
A positive net moment indicates that angular acceleration is occurring
true
A rigid link model is illustrated in a free body diagram.
true
A static analysis is useful in a materials handling task.
true
An MA > 1 indicates the effort arm exceeds the resistance arm, which magnifies the moment created by the effort force.
true
Angular momentum increases if moment of inertia increases and decreases when angular velocity decreases.
true
Decreasing moment of inertia by going from a laid out to tucked body position when doing a backflip allows one to rotate quicker.
true
For a system to be in equilibrium, all forces and torques must equal zero
true
In a dynamic analysis, the linear and angular accelerations are nonzero
true
In a static analysis, the linear acceleration is constant.
true
Internal work may be either positive or negative
true
Mechanical work can be equated with energy expenditure
true
Once a gymnast leaves the vault, angular momentum remains constant while airborne if air resistance is neglected.
true
Rotational kinetic energy of the foot is more influenced by the foot's angular velocity than its moment of inertia.
true
T/F: An object in motion will not stop unless some external force acts on it
true
T/F: Force is a vector
true
T/F: Gravity and friction are examples of external forces
true
T/F: High frictional forces on a surface can be a trip hazard for someone walking on that surface.
true
T/F: If a 100 N force is applied to lift an object with a mass of 10 kg, that object will be accelerate upward
true
T/F: Laminar flow is most likely to occur when the object passing through the fluid is small, has a smooth surface, and is moving slowly
true
T/F: Only the force component tangential to the rim of a wheelchair causes propulsion
true
T/F: The amount of energy transmitted from you to the water when swimming is proportional to the disturbance of the water
true
T/F: The center of pressure can distinguish between runners who pronate versus those who do not.
true
T/F: Two pushing and pulling forces acting on the same point at the same time can be added together and represented as one resultant force
true
T/F: When you are standing still, the sum of all of the external forces acting on your body always equals zero
true
T/F: With a similar swing speed, a longer golf club will result in a greater tangential velocity
true
T/F: while a force can pull or push an object, your muscles can only technically pull, or create tensile forces
true
The inertial force in a dynamics analysis is the product of the moment of inertia and the angular acceleration.
true
The moment arm is always measured from the point of application of the force to the axis of rotation.
true
The moment of inertia about an axis through the center of mass is less than the moment of inertia about any other perpendicular axis running through any other point on the segment.
true
The only force creating a moment about the shoulder when an arm is held out to the side is the weight of the entire arm.
true
Third-class levers, where the effort and resisting forces are on the same side of the fulcrum, are most prominent in the body.
true
To balance a first-class lever, the moments at both ends must be equal.
true
To determine the net moment acting at the ankle joint, all moments acting on the system must be evaluated.
true
Total body angular momentum can be increased during a dive by forcefully swinging the arms downward.
true
When an ice skater is spinning, to stop they increase the moment of inertia.
true
You performed vertical jumps on a force platform two times. The time you generated greater vertical impulse was the time you jumped higher
true
if the center of mass is not elevated during walking, no external work is done
true
if the moment arm is greater than the resistance arm, the lever is a second-class lever.
true