HES 370 Quiz Questions #2
Bob is trying to push a box across the room. When Bob pushes on the box (applying force), the box applies an equal and opposite force applied to Bob. This concept is known as... a) friction force b) coefficient of friction c) rolling friction d) none of the above
A) friction force
Friction: a) opposes the direction of motion b) acts in the direction of motion c) A and B d) B and C
A)opposes the direction of motion
If GRF > W, A. Acceleration is positive B. Acceleration is negative C. Velocity is constant D. Velocity is zero
A. Acceleration is positive
Which direction is the force of friction moving in at heel strike (in relation to your movement)? A. Backward B. Forward C. Upward D. Downward
A. Backward
what is the description of change in CoM speed for segment G? A. Decrease Speed downward B. Decrease Speed Upward C. Increase Speed downward D. Increase Speed upward
A. Decrease Speed Downward
SSC= a. a spinal reflex b. an eccentric muscle contraction followed immediately by a concentric muscle contraction c. an eccentric phase of CMJ that alters the properties of the contractile elements and enhances the development of force d. practice effect
B
59. Which formula is Incorrect? A. Summation of Force = mass * acceleration B. GRF = ma C. P = mv D. Flim = μR
B. GRF = ma
Once you start moving an object, the limiting value of friction drops A) 50% B) 10% C) 20% D) Not at all
C. 20%
What isn't related to Inertia A. Newton's 1st Law B. property of a body to resist change in it's state of motion C. If one body exerts a force on a second body, the second exerts a force back on the first equal in magnitude but opposite in direction. D. "body at rest will stay at rest, body in motion will continue to move with same speed in the same direction"
C. If one body exerts a force on a second body, the second exerts a force back on the first equal in magnitude but opposite in direction.
The law that states if one body exerts a force on a second body, the second exerts a force back on the first equal in magnitude but opposite in direction is considered... a. Newtons 1st law b.The Law of Friction c. Newtons 3rd law d. The Law of Thermodynamics
C. Newtons 3rd Law
Which of these factors influence rolling resistance? a) deformability of surface b) diameter of rolling object c) force pushing the surfaces together d) all of the above are factors that influence rolling resistance
D) all of the above are factors that influence rolling resistance
Factors that affect the limiting value of friction include, a) The normal reaction force - the force pressing the two object together b) The coefficient of friction - the nature of the 2 surfaces in contact c) The area of contact between the two surfaces d) Both A and B e) All of the above
D)Both A and B
Which of the following factors affect rolling resistance: 1) Hardness of surfaces 2) Force pushing surfaces together 3) Diameter of the rolling object A ① and ③ B ② and ③ C ① and ② D All of the above E none of the above
D. All of the above
Which of the following does NOT explain why a countermovement jump is more successful A. Time for development of force B. Spinal reflexes C. Force potentiation D. All of the above are possible explanations
D. All of the above are possible explanations
The magnitude of rolling resistance is affected by A. Deformability B. Forces pushing surfaces together C. Diameter of the object that is rolling D. All the Above
D. All the above
All of the following regarding CMJ and SJ are true except: A. CMJ allows for greater joint movement and moment B. CMJ recruits more motor units/muscle fibers C. SJ is not apart of practice effects D. SJ allows for the development of elastic energy
D. SJ allows for the development of elastic energy
A positive acceleration is: a) an increase in speed upwards b) a decrease in speed upwards c) a decrease in speed downwards d) an increase in speed downwards e) all of the above e) A and C
E)A and C
The types of friction are A) Kinetic B) Static C) Dynamic D) Ballistic E) A and B F) All of the Above
E. A and B
What is force? A. a push or a pull applied to an object B. the effect of one body on another C. something needed to change the state of motion of an object D. it causes acceleration E. all of the above
E. All of the above
T or F: Momentum is the product of mass and acceleration.
False
T or F: Newton's 2nd Law states that there is never a single force, but always a pair of forces that are equal in magnitude but opposite in direction.
False
T/ F Newton's third law of motion states that if one body exerts a force on a second body, the second body exerts a force back on the first equal in magnitude and the same direction.
False
T/ F The SSC, stretch shorten cycle, can be defined as a concentric contraction immediately followed by an eccentric contraction.
False
T/F - Static and kinetic are two friction states for rolling friction.
False
T/F The point of application is where the center of mass is
False
T/F When two surfaces are in contact, a friction force will ALWAYS develop
False
True or False: One way to achieve a negative acceleration is to increase center of mass speed as the center of mass moves upward.
False
True or false: Newton's 3rd Law of Motion states that there will never just be a single force, but always a pair of forces, equal in both magnitude and direction.
False
True or false: Newtons 3rd Law states that a body at rest will stay at rest and a body in motion will continue to move with the same speed and direction.
False
True or false: When you slam on breaks and a bag of groceries in the front seat spill everywhere, this relates to Newton's 3rd Law of Motion (action-reaction).
False
True/ False: Friction is NOT a resistive force.
False
True/False The Stretch Shorten Cycle is defined as the concentric muscle contraction immediately followed by an eccentric muscle contraction.
False
True/False in order for an object to move, the sliding force has to be lower than the limiting force
False
True/False: The only type of friction is sliding friction
False
μ is the coefficient of friction and it is only depend on temperature.
False
The CMJ is more successful than the SJ for all of the following reasons EXCEPT: A) Time for development of force B) Storage of elastic energy C) Jump height D) Force potentiation
Jump Height
T or F: Pressure is inversely proportional to the amount of surface area.
True
T/F If forces are equal in magnitude, they do not cancel each other out
True
T/F Rolling resistance is resistance to motion produced when one surface rolls over another surface. When applying the concept to car tires, rolling friction has implications for gas economy.
True
T/F The two types of friction are sliding friction and rolling friction.
True
T/F: In impact situations, we want to spread the force over an area rather than being concentrated at a single point.
True
True or False : Friction opposes motion of sliding object
True
True or False: Gravity plays a role on the effects of friction even when the object is on a flat surface.
True
True or False: Inertia is, a property of a body to resist a change in its state of motion
True
True or False: The limiting value of friction is the limit to the magnitude of the friction force and the amount of force needed to overcome an object
True
True or False: There needs to be a force applied to have friction
True
True or False: You can have friction without movement, but you cannot have friction without force.
True
True or false: there are two different types of friction.
True
True/False: A counter movement jump has a stretch shorten cycle that a squat jump does not.
True
True/False: Newton's 3rd law of motion is the "law of action/reaction"
True
All of the following are true regarding friction except: a) It occurs when there is an attempt to cause sliding b) It opposes the motion of the sliding object c) There are two states: static state and kinematic/dynamic state d) There are two types: sliding and rolling
a) It occurs when there is an attempt to cause sliding
Something going downwards and decreasing speed is a) positive acceleration b) negative acceleration c) neither
a) positive acceleration
According to Newton's 3rd Law, there is never just a single force but always a pair of forces that are a. equal in magnitude and opposite in direction b. equal in magnitude and in the same direction c. unequal in magnitude and opposite in direction d. unequal in magnitude and in the same direction
a. equal in magnitude and opposite in direction
When you are decreasing speed and moving downward, you are experiencing a. positive acceleration b. negative acceleration c. both d. neither
a. positive acceleration
What is a stretch shorten cycle? a) The eccentric phase of muscle contraction b) eccentric muscle contraction followed by a concentric muscle contraction c) The concentric phase of muscle contraction d) None of the above
b) eccentric muscle contraction followed by a concentric muscle contraction
Countermovement jumps are more successful than squat jumps for all of the following reasons EXCEPT: a) CMJ has greater practice effects b) CMJ allows for less time for development of force c) CMJ allows for storage and reutilization of elastic energy d) CMJ uses the stretch-shorten cycle
b)CMJ allows for less time for development of force
Impulse is defined as a.) force needed to move an object b.) the change in momentum c.) Pressure spread over a surface d.) the chance in pressure
b. The change in momentum
Which of the following does not influence the magnitude of rolling resistance? a. hardness of surface b. speed of the rolling object c. diameter of the rolling object d. force pushing surfaces together
b. speed of the rolling object
Which kinematic variable allows us to measure changes in the state of motion of an object? a) Velocity b) Force c) Acceleration d) Displacement
c) Acceleration
If GRF is = W then a) Sum of forces > then 0 b) Sum of forces < then 0 c) Sum of forces = 0 d) None of the above
c) Sum of forces = 0
Which of the following is NOT true. a) GRFv is the vertical component of the ground reaction force b) W is the person's body weight c) aCoM is the horizontal acceleration of the CoM. d) mb is the person's body mass
c) aCoM is the horizontal acceleration of the CoM.
Newton's 3rd Law explains how when we push against the ground with our bodies, the ground pushes back against us with an equal and opposite force. Which concept does this example describe? a. Friction Force b. Gravitational Force c. Ground Reaction Force d. Counter Movement Jump
c. Ground Reaction Force
Pressure is... a) the force applied per cross sectional area b) measured in N/s2 c) equal to force/area d) a & c e) b & c
d) a & c
Which of the following is true about GRF a) it is arguably the most important external force acting on the body b) it is largely under our control through our coordinated muscle actions c) when we push against the ground, the ground pushes back against the body with an equal and opposite force d) all of the above
d) all of the above
The magnitude of rolling resistance is influenced by which factor(s)? a. Hardness of surfaces (deformability) b. Force pushing surfaces together c. Diameter of the rolling object d. All of the above
d. All of the above
Sliding friction is dependent upon: a. the type of surface b. the mass of the object c. the force pushing the surfaces together d. a and b e. all of the above
d. a and b
Which of the following is TRUE about Rolling Resistance (RR)? a) RR will be less than sliding friction b) RR is primarily due to a deformation in the surfaces in contact c) RR is influenced by the force pushing surfaces together d) RR is influenced by the diameter of the rolling object e) All of the above
e) All of the above
What are the different types of friction? a) static friction b) rolling friction c) sliding friction d) a and b e) b and c f) all of the above
e) b and c
Positive acceleration occurs when: a. Decrease in center of mass speed as it moves downward b. Decrease in center of mass speed as it moves upward c. Increase in center of mass speed as it moves downward d. Increase in center of mass speed as it moves upward e. A and D f. B and C
e. A and D
What forces act on a box on a flat surface that has been given a small push, but no movement has occurred? a. no forces act on the box b. the force of gravity and the normal force c. the applied force of the push d. the force of friction e. b, c and d are all forces acting on the box
e. b, c and d are all forces acting on the box
