Biomechanics Final

The maximum limiting friction that can be generated between the bag and the cart is 50N. You need to slide the bag to the side of the cart. If you apply 50N horizontally on the bag

the bag will remain motionless

What is the relationship between torque and angular acceleration?

the greater the torque acting at the axis of rotation, the greater the angular acceleration of a given body

During angular motion, what is the relationship between the length of the moment arm and the torque created (when the force used is constant)?

the longer the moment arm, the greater the torque

Poisson's Ratio refers to

the ratio of strain in the axial direction to strain in the transverse direction for each different type of material

What lever is used when you raise your forearm during a bicep curl?

third

A load that produces twisting of a body around its longitudinal axis is called

torsion load

Hip rotation occurs in what plane?

transverse (horizontal)

If a runner completes a 400-meter sprint around a 400 m track in 50 seconds, what is the runner's displacement with respect to the starting position?

0m

The coefficient of static friction between the sole of an athletic shoe and the basketball court floor is 0.80. Bill wears these shoes when he plays basketball. If Bill exerts a normal contact force of 1420N when he pushes off of the floor to run down the court. How large is the friction force exerted by his shoes on the floor?

1136NN

A 250lb shot-putter pushes forward and upward on an 8lb shot with a force of 1100N. This force acts at an angle of 40 degrees above horizontal. How much of this 1100N force acts in the upward direction?

809N

A 75kg weightlifter exerts a 1600N force upward on a 175lb barbell. How large is the net force acting on the barbell?

822N

As the velocity of a concentric contraction increases, the maximum force a muscle can produce increases - in other words, the faster your arm can move to throw a ball, the more force the arm muscles can exert on the ball.

False

Choking up on a baseball bat and shortening its length will increase the angular velocity of the bat.

False

Identify the true statement.

Increasing the magnitude of a force acting on a surface area increases the amount of stress acting on the surface.

The research on the tension-length relationship of muscles indicates that a muscle is capable of generating maximal force when the muscle is

slightly longer than resting length

The study of forces that cause or tend to cause motion is

kinetics

torque is

-the tendency of a force to cause rotation -the compression and distraction effects of a force -the product of force and moment arm

The horizontal velocity of Serena's tennis serve is measured as 100m/s. Horizontally, the ball travels 20m before reaching her opponent. If the ball didn't slow them down when it bounced or because of air resistance, how long would it take to reach her opponent?

0.20s

George runs the football 20 yards straight downfield then 7 yards to the right before he is tackled. What was George's resultant displacement in yards?

21.2 yards

George runs the football 20 yards straight downfield then 7 yards to the right before he is tackled. What was George's distance in yards?

27 yards

A 60kg volleyball player lands from a jump and tries to stop her forward motion. The normal contact force exerted by the floor on her shoes in 2800N. The friction force exerted by the floor on her shoes is 800N acting backward on the player. What is the resultant ground reaction force exerted by the floor on the volleyball player's shoes?

2720N

Ariel is running a 100m dash. When the start pistol fires, she leaves the starting block and continues to speed up until she reaches her top speed of 11m/s 3s into the race. She holds this speed for 5s and then gradually slows down until she crosses the finish line 11s after she started the race. What is Ariel's average acceleration during the first 3s?

3.67m/s^2

Ariel is running a 100m dash. When the start pistol fires, she leaves the starting block and continues to speed up until she reaches her top speed of 11m/s 3s into the race. She holds this speed for 5s and then gradually slows down until she crosses the finish line 11s after she started the race. What is Ariel's average velocity for the whole race?

9.09 m/s

As a projectile is thrown into the air, its horizontal velocity decreases on the way up to 0m/s at the top but increases on its way down at a rate of 9.81m/s.

False

Identify the true statement.

Increasing the surface area over which a force is distributed decreases the amount of stress acting on the surface.

The principle of conservation of momentum restates

Newton's first law

The statement "a rotating body will maintain a state of constant angular motion unless acted on by an external torque" can be applied to a merry-go-round that is in constant motion. Which of newton's laws applies to this concept?

Newton's first law

A ball being held by someone running will continue to move in the same direction and with the same speed until the runner causes a chaTnge in the motion of the ball. This best exemplifies

Newton's first law of motion

The moment arm distance for a muscle force changes throughout the range of motion.

True

When performing a vertical jump for maximal height, muscle spindles and golgi tendon organs play a significant role in explosiveness. Why does jumping following a quick squat allow for greater height than jumping after holding a squat for a few seconds?

When going into a squat for a few seconds, muscle spindles are recruited and their response is muscle contraction

If you fracture your femur, you will be told by your medical provider to start to weight bear as soon as the fracture site closes because of what guiding principle?

Wolff's law

The force that acts parallel to an object in contact with a surface and may result in the formation of blisters is called

a shear force

When a sprinter uses starting blocks to enhance running performance, which of Newton's laws is best represented by the interaction of the sprinter and the blocks?

action-reaction

When performing a bicep curl, the biceps brachii is the __________ and the triceps brachii is the __________

agonist; antagonist

The left fielder throws a baseball home from 60km away. The ball's horizontal velocity is 30m/s and its vertical velocity is sufficient to keep it in the air until it reaches the catcher at home plate. At the same time, a base runner is running toward home plate. His velocity is 5m/s and he is 5m from home plate. If the base runner's velocity stays consistent and air resistance isn't a factor, which will arrive at home place first, the baserunner or the baseball and why?

baserunner, takes 1 second to reach home plate

Bone is strongest in resisting

compressive stress

When articular cartilage is exposed to constant compressive stress, the strain in the cartilage will increase gradually with time. This pattern is called

creep

Kinematics is the branch of mechanics that

describes the pattern of motion

While walking and then running at a constant speed with the same ball, you want to release each ball in time for it to land in a target. In order for the ball that you run with to hit the target, when would you have to release the ball you run with relative to the release of the ball you walk with?

earlier than the ball you walk with

When going down into a squat, the quadriceps muscles control the movement at the knee via _________ contraction

eccentric

When you stretch your hamstrings and they return to their original length upon release, this is called

elastic

Muscles have the unique properties of extensibility, contractility, elasticity, and

excitability

Shoulder abduction occurs in which plane?

frontal (lateral/coronal)

If a bag has a mass of 40 kg, how much force must you apply vertically to lift it?

greater than 392N

If you increase the time during which a constant force is applied to an object, what effect does this have on the impulse given to the object?

it increases the impulse

While running at a constant speed with 2 balls of different weights, you drop the balls at the same time while running past a target. Both balls continue to move in the same direction as the runner upon release as they descend to the ground. Assuming air resistance is negligible, why do the balls hit the ground at the same time?

law of universal gravititation

What type of bone is the fibula?

long

What quantity is the same in space as it is on Earth?

mass

The coefficient of dynamic friction between the grass and a 300 kg football blocking sled is 0.35. If a 100 kg football player only pushes horizontally against the sled, how large must the horizontal force be to keep the sled moving at constant velocity?

not 392N

When you stretch your hamstrings and then they assume a new "normal" length upon release, it is called

plastic

Knee flexion occurs in which plane?

sagittal (anteroposterior)