Biomechanics final exam quiz questions

Usain Bolt ran the 100-meter dash in 9.58 seconds. What was his average acceleration?

+1.1 m/s2

This ballet dancer begins her pirouette with an angular velocity of 0. If she reaches an angular velocity of +510 o/s in .9 seconds, what was her body's average angular acceleration?

+567 degrees per second squared

An example of using impulse to safely decrease momentum would be to __________.

---

During a tip-off, the referee throws a ball straight upward at 1.2 m/s. What is the vertical acceleration at the top of the flight?

-9.81 m/s2

The person is doing a shoulder flexion exercise. If their shoulder moves from a relaxed position (0o) to the position below (95o shoulder flexion), what is the angular displacement? Analyze with the assumption that the person is facing left as shown.

-95 deg

The average horizontal velocity of a penalty kick in soccer is 22 m/s. The horizontal displacement of the ball from the kicker's foot to the goal is 11m. How long does it take for the ball to reach the goal after it is kicked?

.5s

During a tip-off, the referee throws a ball straight upward at 1.2 m/s. What is the vertical velocity at the top of the flight?

0

You are doing a deltoid/shoulder raise from a standing position. The weight is 30 lbs (133N) and the distance from your elbow to the weight is 40 cm. What is the total torque produced by the weight if your shoulder is in neutral/you are holding it straight down?

0Nm

During a tip-off, the referee throws a ball straight upward at 1.2 m/s. What is the vertical velocity at the instant the ball leaves his hand?

1.2 m/s

This person is spinning around as she prepares to do a hammer throw. If her entire body completes exactly 3 spins, and all three spins together take .95 seconds, what is her body's average angular velocity?

1137 deg/s

In a projectile motion problem, if the projectile is a parabola, you can multiply the time by ____ to get the total time in the air.

2

Assume the sprinter is pushing straight back into the blocks with 500N (parallel to the track) and straight down into the blocks with 2500N (perpendicular to the track). What is the resultant force?

2550 back and down

Three players are pushing on the same football sled forward (+). Player A pushes with 100N Player B pushes with 150 N Player C pushes with 200N Which answer best represents the net force acting on the sled?

450 N forward

The weight of the ball on the hill has a downward force of -700N. The incline of the hill is 35 degrees. What is the amount of force that is pushing the ball against the hill?

573N against the hill

During men's basketball conditioning, the team must run 200 m in 32 seconds. What average velocity must they have?

6.25 m/s

Assume the diver pushed away from the diving board with 10N (away / parallel to water) and vertically up into the air with with 60N. What is the resultant force?

61 N up and away from the board

Harris ran a 400 meter race in 41.8s. What was his average speed for the race?

9.6 m/s

For a body to be in static equilibrium _______________.

All external forces acting on the body must sum to zero The body must be stationary All torques acting on the body must sum to zero

Rate of change of angular velocity; expressed in units of angular displacement divided by time squared or expressed in radians per second per second or revolutions per second per second; a vector quantity.

Angular acceleration

Change in absolute angular position experienced by a rotating line with the direction of the change indicated; the angle between a line segment in its initial position and in its final position with the direction of rotation noted; measured as units of angular position or expressed as radians, degrees or revolutions.

Angular displacement

A system for locating the position of a point in two (or three) dimensions; the two (or three) coordinates represent displacements from a fixed point or origin in specific directions at right angles to each other.

Cartesian Coordinates

A hiker spends all afternoon hiking a winding path through the woods. She ends up back at the parking lot at the end of the hike. She looks at her FitBit and it says she hiked 8 miles. What was her distance and what was her displacement?

Distance = 8 miles; Displacement = 0 miles

Starting from anatomical position, the ankle joint action that occurs around a transverse axis and causes the foot to move in a sagittal plane such that it moved forward and upward toward the leg.

Dorsiflexion

The human skeleton serves 5 primary functions; three are mechanical and two are physiological. Choose the answer that best represents a physiological (non-mechanical) function of the skeletal system.

Hemopoiesis

Shiny, white, smooth cartilage that makes up the articular cartilage covering the articular surfaces of bones in synovial joints.

Hyaline cartilage

Mass of an object times the linear velocity of the object; measured in units of mass times units of length divided by units of time or as kilogram-meters per second in SI; a vector quantity.

Linear Momentum

The quantity of matter in an object.

Mass

If a horizontal force to the left is applied to a body that is in uniform motion to the right, the body will ____________________.

Negatively Accelerate (aka decelerate)

A subconscious mechanism by which body is able to control posture & movement by responding to stimuli originating in proprioceptors of the joints, tendons, muscles, and inner ear.

Proprioception

Jonathan is doing a seated knee extension exercise. The weight he is lifting (50 lbs = 222N) is at his ankle and his quadriceps inserts about 6cm from his knee. What do we know about the force that his quadriceps must produce?

Quad Force > Weight Force

Force or stress acting parallel to the analysis plane or perpendicular to the long axis of the object; tends to slide molecules past each other and skew the object.

Shear

Which represents the correct order to solve a projectile motion problem?

Solve vertical equations then horizontal equations

I am trying to determine how much force a biceps must create when doing an isometric biceps curl of a given weight. If I know (because I can measure) the moment arm for both the biceps and the weight, which equation is most appropriate?

T1=-T2

What happens to your center of gravity when you add a 200 N suitcase to your hand held out to your side?

The center of gravity shifts in the direction of the suitcase

Jonathan is doing a seated knee extension exercise. If we know that his quadriceps is creating 8,000N of torque in the counterclockwise direction, what do we know about the torque of the weight that he is lifting if we assume the system is in equilibrium?

The torque of the weight is -8,000N

A load that causes an object to twist due to torque; torques in opposite directions acting on either end and around the longitudinal axis of an object produce shear stresses in the analysis plane that become larger with increased distance from the longitudinal axis; as a result of a torsion load, an object will deform by twisting.

Torsion

"The strength of bones will increase according to the lines of physical stress placed upon them." What is the name of the above rule?

Wolffs law

Rate of change in velocity; expressed in units of length per unit of time squared or in meters per second per second (m/s2) in SI; a vector quantity.

acceleration

The complete ossification of long bones generally occurs by the end of ________________________.

adolescence

The study of the mechanics as it relates to the functional and anatomical analysis of biological systems and especially humans.

biomechanics

Porous, less dense bone tissue found deep to cortical bone near the ends of long bones; also referred to as spongy or trabecular bone.

cancellous bone

An external force directed through the center of gravity of an object is known as:

centric force

This male figure skater must pull the female skater towards him in order to cause her to rotate around him. If their hands slip, and he lets go, she will fly off in a straight line. The puling action is due to __________ acceleration whereas the flying action is due to __________ acceleration.

centripetal / tangential

Consider in the above picture. The woman is doing a deadlift. She must lift the weight from the floor until she is standing upright. The force of the weight acts down. The force of her hands acts up. Consider only those two forces.

colinear

My athlete is hanging from a chin-up bar and pulling himself up very quickly. What type of contraction is this?

concentric contraction

Consider in the above picture. The ball handler is about to be impacted by three different players. One player will hit him from the front-right side. Another will hit him from behind. A third will hit him from the left side. Consider only those three forces.

concurrent

The hamstring muscle is able to generate force against resistance when stimulated. This occurs because muscle has which property?

contractility

Material behavior characterized by a continued increase in strain under a constant stress.

creep

Cartilage does not have a blood supply, so it relies on _____________________ to get nutrients.

diffusion

Change in the location of a point expressed as the length and direction of the vector from the starting position to the ending position; expressed as units of length or as meters in SI.

displacement

The red dot (on ankle) is ____________________ to the blue dot (on hip).

distal

If you perform a lateral arm raise with a weight in your hand, if you bend your elbow to perform the exercise rather than keep your elbow straight, the exercise will become

easier

Able to return from a deformed shape to the original dimensions when the stress causing the deformation is removed.

elastic

Point on the stress-strain curve beyond which plastic deformation will occur; also referred to as the proportional limit.

elastic limit

When the net forces acting on an object are zero. The object is not moving/accelerating.

equilibrium (static)

Starting from anatomical position, the joint action that occurs around an anterior-posterior axis through the ankle when the lateral side of the sole of the foot is lifted.

eversion

Strain at which a material breaks or fails.

failure strain

Half of the fibers in a motor unit will contract if the stimulus is half as much.

false

There is a greater change of tendon injury if a load is applied slowly compared to if the same load is applied quickly.

false

Joint in which fibrous connective tissue joins bones together making it immovable

fibrous joint

The components of a lever include an axis or fulcrum, resistance, and

force

Match the exercise below to the plane of motion. Side bend

frontal plane

The weight is 25 lbs (11.3 kg). How much force must the woman create in order to lift the weight?

greater than 111N upwards

When I endurance train my muscles, they will _________________.

have increased o2 metabolism

Average force times the duration of application of the force; causes and thus is equal to change in linear momentum; measured in units of force times units of time or expressed as newton seconds in SI; a vector quantity.

impulse

Which quantity causes a change in linear momentum?

impulse

The property of an object to resist changes in its motion.

inertia

As the mass of an object decreases, what happens to its inertia?

it decreases

The branch of dynamics concerned with the description of motion (as apposed to the forces causing the motion).

kinematics

Which concept is best described as "inertia in motion"?

momentum

Concentrated primarily in muscle belly between the fibers, sensitive to change in length of the muscle (aka stretch), and protect by resisting the stretch on the same side

muscle spindle

What type of cell creates bone?

osteoblast

Which condition results as people age or if they have a past traumatic injury to a bone/joint?

osteoporosis

An imaginary two-dimensional surface through which a limb or body segment is moved.

plane of motion

Able to maintain a deformed shape when the stress causing the deformation is removed.

plastic

An athlete attempts to stretch their hamstring. They use their full body weight and hold the stretch for nearly three minutes. After the stretch, the hamstring is longer than it was before. What word best describes this concept?

plastic behavior

Ratio between transverse strain and strain in the axial direction for an object loaded axially.

poissons ratio

Location of a point in space relative to some fixed point.

position

An object that has no external forces acting on it other than the force of gravity.

projectile

The joint action that occurs around an anterior-posterior axis through the wrist joint and causes movement of the hand in a frontal plane in the direction of the thumb; the opposite of ulnar deviation; also referred to as abduction or radial flexion.

radial deviation

An external contact force that results when one object touches another.

reaction force

In which position will a muscle be the most able to generate force?

resting length

Match the exercise below to the axis of rotation (at the hip). situp

sagittal axis or AP axis

An example of a flat bone is _____________________.

scapula

Assist in the action of agonists. The combined action of two or more muscles that cross the same joint to produces the desired result.

synergist muscle

A ball-and-socket joint is classified as a _________________________.

synovial joint

A freely movable joint characterized by a joint cavity

synovial joint

Four tug-of war participants are playing for Team A and four are playing for Team B. Player A1 pulls with 100N force. Player A2 pulls with 100N force. Player A3 pulls with 50N force. Player A4 pulls with 100N force. Player B1 pulls with 100N force. Player B2 pulls with 100N force. Player B3 pulls with 50N force. Player B4 pulls with 50N force. Which team will win? How much more force can that team produce?

team A will win bc they have 50N more force

Cord or sheet of collagenous connective tissue that attaches muscle to bone

tendon

The man in the grey is "spotting" the bench press. Assume the weight is 1,000N. The weightlifter produces an upward force of 1,100N on the bar. How much force does the spotter need to use in order to assist?

the spotter does not need to assist

You are sitting here taking this quiz. The force your body exerts downward is equal and opposite to the force the chair is exerting upwards on your body. Which of Newton's Laws explains this concept best?

third

If I have the initial horizontal velocity, what variable to I also need to know in order to determine horizontal displacement of a projectile?

time in the air

A football player's ankle is being held by another player in a pile up. He falls and his body rotates around his fixed ankle. He sustains a fracture of his tibia (shin bone). Which type of stress most likely caused his fracture?

torsion stress

A torque produced by a force is known as a moment of force.

true

If I lift heavy weights regularly, my muscles and tendons will both get bigger.

true

The amount of strength generated will depend on the number of motor units that are activated as well as frequency of stimulation.

true

The muscle spindle is responsible for the "stretch reflex".

true

Mathematical representation of any quantity that is defined by its size or magnitude (a number) and its direction (its orientation).

vector

Measure of the force of gravity acting on an object; mass times the acceleration due to gravity; expressed as newtons in SI.

weight

The measure of the force of gravity acting on an object.

weight