Biomechanics FINAL

In a vertical jump landing from initial foot contact to a complete stop, people normally bend knees to reduce the amount of change in momentum during landing. T/F

False

Instantaneous velocity of basketball free throw at release is greater than the instantaneous velocity of the ball before entering the basket. (ignore air resistance and consider only the magnitude.) T/F

False

Kinetic variables include impulse, displacement, speed, and power. T/F

False

Locomotion speed is equal to stride length multiplied by stride time. T/F

False

The directions of radial and tangential accelerations are 45 degrees to each other. T/F

False

The units for kinetic energy, impulse, and work are all the same. T/F

False

When a body is in the air, the torque produced on the body by gravity is increased. T/F

False

When extending forearm slowly during armcurl, the triceps is active concentrically. T/F

False

You can hit a golf ball farther with a longer club because you can swing faster (i.e., greater angular velocity of club). T/F

False

The angle of attack of a projectile affects not only lift but also drag. T/F

True

When muscles produce eccentric contraction, they produce negative work. T/F

True

While spinning with arms out on a frictionless chair, you will start spinning faster when bringing arms closer to the body and produce a greater angular momentum. T/F

True

What can be generally done to increase stability? a. Lower COM (center of mass) b. Decrease BOS (base of support) c. Move COM to edge of BOS d. Decrease body mass

a. Lower COM (center of mass)

Which of the following is NOT true about the value of -9.81m/s2 of an object in projectile motion? (ignore air resistance) a. Release speed does affect the value. b. Object can be accelerating or decelerating. c. In reality, it can be different depending on where you are on earth. d. Object can be going up or coming down.

a. Release speed does affect the value.

In the standing position, from the moment you bend your knees and coming to a stop at 90 degrees, the body initially accelerates and then decelerates to stop. When is the transition point from deceleration to acceleration? a. When acceleration is zero. b. When gravity is zero. c. When ground reaction force is zero. d. When ground reaction force is greater than gravity.

a. When acceleration is zero.

Three identical tennis balls are hit so that they leave their respective tennis rackets at the same heights, speeds, and angles of release (let's assume 45 degrees). One is hit with topspin, another backspin, and the other with no spin. When considering air resistance, Which ball will reach a higher peak before making contact on the court? a. top spin b. back spin c. no spin d. all at same height

a. back spin

The center of rotation at a given joint angle during a dynamic movement is called ( ) center. a. instant b. relative c. absolute d. rotation

a. instant

An area bound by the outermost regions of contact between a body and support surface defines what? a. stability b. balance c. base of support d. equilibrium

c. base of support

Which of the following is NOT a direct influencing factor of projectile motion (ignoring air resistance) at the point of release? a. release speed b. release angle c. release acceleration d. relative height of release

c. release acceleration

Rolling friction is not influenced by which of the following? a. weight b. radius c. width d. deformability

c. width

Which of the following is a scalar? a. displacement b. momentum c. work d. velocity

c. work

Which factor affects both skin drag and form drag? (It increases one drag but decreases the other.) a.Cross-sectional area b.Shape of body c.Smoothness of surface d.Surface area

c.Smoothness of surface

If a long jumper can maintain maximum running speed, the optimal takeoff angle would be 30 degrees. T/F

False

If a person jumps straight up in a layout position with arms up but lands with arms down, the time from takeoff to peak is shorter than the time from peak to landing. T/F

False

Three identical tennis balls are hit so that they leave their respective tennis rackets at the same heights, speeds, and angles of release (let's assume 45 degrees). One is hit with topspin, another backspin, and the other with no spin. When considering air resistance, Which ball will likely possess the least amount of linear momentum after it contacts the court? a. top spin b. back spin c. no spin d. all possess same linear momentum

no spin ? Or backspin

If a ball bounces up to 1 m when dropped from 2 m above the ground, then it will bounce up to 2 m when dropped from 3 m. T/F

False

If a ball lands on a complete frictionless floor, it will lose angular momentum after the impact on the floor. T/F

False

What force causes radial accelerations?

Centripetal Force

The major advantage of fosbury high jump technique over others is the reduction of ( ) height.

Clearance

Pair of equal, oppositely directed forces that act on opposite sides of an axis of rotation to produce torque is called a ( ).

Couple

A diver is doing a pike front dive with her arms fully extended overhead and her body straight at the instant of takeoff with some amount of angular momentum (H ≠ 0). During the first half of the dive, she brings her hands down toward her feet (i.e., from straight to pike position). What happens to each of the following quantities during that time? (Enter either increase, decrease, or the same as an answer.) The moment of inertia about the transverse axis through her center of gravity (COG)

Decrease

Conversion factor is needed to compute time parameters such as projectile flight time or running stride time T/F

False

Energy, work, and power are all vectors. T/F

False

Name a couple pieces of equipment commonly used in biomechanical analysis of human motion. These were used and demonstrated in class and were also shown in many sports science episodes.

Goniometer, Tracker, Slow Motion Video Camera, accelerometer, pressure sensor

Torque is also called ( ) of force.

Moment

( ) is inverse of speed and is commonly quantified as minutes per km or minutes per mile.

Pace

A diver is doing a pike front dive with her arms fully extended overhead and her body straight at the instant of takeoff with some amount of angular momentum (H ≠ 0). During the first half of the dive, she brings her hands down toward her feet (i.e., from straight to pike position). What happens to each of the following quantities during that time? (Enter either increase, decrease, or the same as an answer.) The angular momentum of her body about the transverse axis through her COG?

Same

A diver is doing a pike front dive with her arms fully extended overhead and her body straight at the instant of takeoff with some amount of angular momentum (H ≠ 0). During the first half of the dive, she brings her hands down toward her feet (i.e., from straight to pike position). What happens to each of the following quantities during that time? (Enter either increase, decrease, or the same as an answer.) The moment of inertia about the longitudinal axis through her COG

Same

A diver is doing a pike front dive with her arms fully extended overhead and her body straight at the instant of takeoff with some amount of angular momentum (H ≠ 0). During the first half of the dive, she brings her hands down toward her feet (i.e., from straight to pike position). What happens to each of the following quantities during that time? (Enter either increase, decrease, or the same as an answer.) The torque produced by gravity on her body about the transverse axis through her COG

Same

What are two types of quantities where the sum of each must be zero to maintain a state of equilibrium?

Sum of forces and sum of torques

The ( ) is equal to the change in energy that it produces in the object acted on. (Think of relationships between two quantities.)

The work of force

A defensive lineman in football is trying to block a forward pass. He would be able to reach higher with one hand than two. T/F

True

Gravity or gravitational force is equal to -9.81 m/s2. T/F

True

If a 2 kg soccer ball kicked in the air with 9.81 m/s vertical velocity at impact, how many seconds after the impact will the ball reach the peak? (Wind is blowing horizontally at 10 m/s.) a. 1 sec. b. 2 sec. c. 3 sec. d. 4 sec.

a. 1 sec.

Lifting the head up is an example of which class of lever? a. 1st class b. 2nd class c. 3rd class d. 4th class

a. 1st class

What two fluid forces are formed due to pressure difference? a. Form drag & lift b. Skin friction & form drag c. Wave drag & lift d. Buoyant force & wave drag

a. Form drag & lift

What is the MAIN advantage of the high jumpers that are tall with long legs? a. Greater takeoff height b. Greater flight height c. Smaller clearance height d. Optimal takeoff angle

a. Greater takeoff height

Three identical tennis balls are hit so that they leave their respective tennis rackets at the same heights, speeds, and angles of release (let's assume 45 degrees). One is hit with topspin, another backspin, and the other with no spin. When considering air resistance, Which ball will hit the court first? a. top spin b. back spin c. no spin d. all at the same time

a. top spin

When performing a somersault in gymnastics, what is the best position to assume to rotate fastest? a. tuck b. pike c. layout

a. tuck

What shows the correct unit? a.Power = Watts b.Energy = Newton c.Work = Pascal d.Impulse = Joule

a.Power = Watts

Which of the following is NOT a correct definition? a. Kinesiology is study of movement. b. Mechanics is studying the cause and effect. c. Torque is moment of inertia times angular velocity. d. Kinematics describes the movement of system.

c. Torque is moment of inertia times angular velocity.

Which of the following statements is TRUE? a. Women have higher center of gravity than men. b. Center of gravity can lie outside the body. c. Center of buoyant force is lower than center of gravity. d. Bigger person has bigger center of gravity.

b. Center of gravity can lie outside the body.

What is the advantage of the hitch-kick technique (running in the air) in long jump? a. Greater angular momentum at takeoff b. Optimal body position at landing c. Greater torque while airborne d. Easier to learn compare to the other techniques

b. Optimal body position at landing

Which of the following is the unit of angle that must be used to compute linear velocity? a. Degrees b. Radians c. Revolutions d. Omega

b. Radians

If velocity is constant, what is NOT true? a. Acceleration is zero. b. Work is conserved. c. Net force is zero. d. Kinetic energy is constant.

b. Work is conserved

Which of the following statements is FALSE? a. Torque is rotary effect produced by an applied force b. Moment arm is the shortest distance from the force's line of action to the axis of rotation. c. If angular acceleration is zero, then torque is zero. d. Moment of inertia does not impact torque.

c. If angular acceleration is zero, then torque is zero.

What force acts perpendicular to the direction of relative flow? a. Form drag b. Angle of attack c. Lift d. Wave drag

c. Lift

Elbow flexion during a biceps curl is an example of ( ) class lever. a. First b. Second c. Third d. Fourth

c. Third

When a ball thrown straight up and reaches its peak height, the kinetic energy is ( ) and vertical acceleration is ( ). a. -9.81 m/s, -9.81 m/s b. 0 m/s, -9.81 m/s2 c. 0 J, -9.81 m/s d. 0 J, -9.81 m/s2

d. 0 J, -9.81 m/s2

Which of the following is NOT a correct definition of momentum? a. Capacity to give impact b. Quantity of motion of a body c. Amount of difficulty of stopping an object d. Ability to reduce pressure

d. Ability to reduce pressure

If a ball is rolling horizontally on the ground at +5 m/s2 and then comes to a stop, what is true? a. Velocity is increasing. b. Rolling friction is acting left. c. Ball is accelerating. d. Ball is going left.

d. Ball is going left.

Which of the following statements is TRUE? a. Speed is a vector. b. Maximum static friction is smaller than dynamic (kinetic) friction. c. Coefficient of friction does have a unit. d. Friction is a passive force.

d. Friction is a passive force.

Which of the following statements is true? a. Kinematics is basically a study of force. b. Displacement may be greater than distance. c. Acceleration is a scalar. d. Statics is studying the system with zero acceleration.

d. Statics is studying the system with zero acceleration.

What shows the incorrect unit? a. Speed = m/s b. Force = N c. Moment of inertia = kg·m2 d. Work = N·s

d. Work = N·s

Which of the following is NOT true? a. WG (work done by gravity) = - ΔPE (potential energy) b. acceleration = change in velocity / change in time c. power = work / change in time d. linear velocity = angular velocity x radius of gyration

d. linear velocity = angular velocity x radius of gyration

Which of the following is the method that uses pre-existing data on individual segment mass and COG (center of gravity) locations? a. suspension method b. balancing method c. reaction board method d. segmental method

d. segmental method

Which of the following statements is FALSE? a.Impulse is accumulated effect of force exertion. b.Force has properties of magnitude, direction, and point of application. c.Friction acts in the direction opposite that of motion or motion tendency. d.Work is the capacity to give power.

d.Work is the capacity to give power.