Biomech Exam 5
If a person has a mass of 80 kg, what is their weight?
-784.8 Newtons -176 pounds
Which is true when applying Newton's 3rd law of action/reaction to dribbling a basketball?
-Action: ball hits floor -Reaction: floor pushes ball
Mass is (ma)
-Measure of inertia -The quantity of matter contained in an object - inversely proportional to acceleration
Force is defined as any influence tending to _____ motion.
-Modify -Change -Cause
When you throw a ball into the air and it reaches its peak in flight, which of the following is true?
-vertical velocity equals 0 -kinetic energy equal 0
A perpendicular force of 300 N is applied to a door 0.5 m from the hinges. What is the torque?
150 Nm
The potential energy of a .045 kg golf ball before it is dropped off the empire state building (381 meters) is approximately
168 J
Which of the following levers would be best to use to move a specific object if your only objective was slight movement of the object?
2nd class with resistance arm of 10 and force arm of 20
If initial height and landing height are the same, the angle of projection that would maximize horizontal displacement is ______ degrees.
45
Which of the following statements is correct concerning momentum?
A 14 lb. bowling ball with a linear velocity of 35 ft/sec will have greater momentum than a 8 lb. ball at 50 ft/sec
Which of the following is Newton's Law of Inertia?
A body in motion tends to remain in motion at the same speed in a straight line unless acted on by a force.
Which of the following represents a scalar quantity?
A mass of 70 kg
Which of the following levers would be best to use to move a specific object if your only objective was speed of the object's movement?
A third-class lever with a resistance arm of 20 and a force arm of 10
Which of the following terms is defined as the rate of change in velocity?
Acceleration
Which of the following could be done to reduce the amount of force needed to move a lever? (wrong)
All of the above -Move the resistance closer to the axis -Apply the force further from the axis -Decrease the amount of resistance
Which of the following statements accurately describes the relationship between linear and angular motion?
Angular motion of the joints produces linear motion
The point at which all of the body's mass and weight is equally balanced or equally distributed in all directions is the _____.
Center of gravity
What does the center of gravity of an object represent?
Center of mass of body
Which of the following equations for linear acceleration is correct?
Change in velocity divided by change in time
Based on the principles of levers, which of the following levers is most efficient in overcoming a resistance of 20 lbs?
EA = 10" , RA = 5"
What is meant by torque?
Effective force producing rotary motion at an axis
Which would be the most efficient manner in which to lift a heavy box?
Face box with elbows bent and arms close to the body
Which of the following is not a part of kinematics?
Force producing motion
Mechanical work involves a _____ and the _____ that it moves through.
Force, distance
Kinematics is the description of motion and includes consideration of each of the following except?
Forces
Which of the following makes it difficult for a runner to change either his speed or direction?
Inertia
Which of the following defines the center of gravity of the body?
Intersection of cardinal sagittal, horizontal and frontal planes
Which of the following is not true regarding the force arm of a lever?
Is determined by multiplying the distance from the axis by force
Which of the following statements is true about kinetic friction?
It is the friction between two objects that are sliding along each other.
Which of the following is the most common form of simple machine found in the human body?
Levers
Which of the following types of machine is most common in the musculoskeletal system arrangements of the human body?
Levers
What is the relationship between the angular and linear velocities of a lever?
Linear velocity is equal to the angular velocity time the length of the lever
The weight of a body is defined as a quantification of the force of gravity acting on which aspect of the body?
Mass
Why is it easier for a runner to move his recovery leg forward more rapidly when it is flexed than when extended?
Momentum of inertia of the leg is less when the leg is flexed
Which is an example of linear motion in sport?
Movement of the center of gravity of a putted golf ball
What is inertia?
Resistance to change in motion
An individual is expecting to be pushed from the left side. What would be the best standing position to assume in order to absorb the force without losing one's balance?
Side stride stance, line of gravity towards left edge of base support
Why is it more difficult to perform a sit-up when the hands are clasped behind the head than when the arms are kept at the side?
The resistance arm is greater
Power equals
work ÷ time
What is the acceleration when the velocity of an object is constant?
Zero