Midterm 1

Question 1

Describe how a speed skater uses impulse during the start of the race and why they take this approach during the start (what does it do?) Explain your answer. Be specific as to how impulse applies to this situation.

Question 2

A 500N gymnast performs a stationary handstand on the high bar. How much force is exerted by the bar in the gymnasts hands?

a) 50N
b) 100N
c) 500N
d) 2500N
e) need more information to calculate

Answer 2

c) 500N

Question 3

When drawing a free body diagram for a dancer pushing off the floor into a jump, which of the following is not a force to be considered?

a) the dancer’s weight
b) the push of the floor on the dancer’s foot
c) the speed f the dancer across the floor
d) the friction of the floor on the dancer’s shoe
e) all of these should be considered
f) none of these are correct

Answer 3

c) the speed of the dancer across the floor

Question 4

An example of a gymnast using impulse to safely decrease momentum, when landing from a dismount from the uneven bars, would be:

a) circling the arms just before contact with the floor
b) landing and flexing with the hips and knees
c) landing with the hips and knees extended
d) only the statements labeled a and b
e) none of these are correct

Answer 4

b) landing ad flexing with the hips and knees

Question 5

Curling rocks have a mass of 19.1 kg (44 pounds). One curling rock is moving down the ice with a velocity of 1.0 m/s and makes direct contact with another rock. The first curling rock stops immediately and the second rock starts to move (this is an example of an elastic collision). What is the velocity of the second curling rock immediately following the collision?

a) 0.1 m/s
b) 10 m/s
c) 0.5 m/s
d) 1 m/s
e) need more information to calculate

Answer 5

d) 1 m/s

Question 6

What is the average velocity of a runner who competes a 100m race in 12 seconds?

a) 1200 m/s
b) 1.2 m/s
c) 8.3 m/s
d) 12 m/s
e) none of these are correct

Answer 6

c) 8.3 m/s

Question 7

Given the example in the picture below, if we were examining the movement for the entire body and how it moves through the sequence, this would best be described as an example of:

• • figure skater skating, jumps and spins three times in air and then lands***
    a) linear motion
    b) rotary motion
    c) general motion
    d) static motion
    e) parabolic motion
    f) none of these are correct

Answer 7

c) general motion

Question 8

A softball is fouled off with vertical velocity of 20 m/s and a horizontal velocity of 15 m/s. What is the resultant velocity of the ball?

a) 20 m/s
b) 25 m/s
c) 30 m/s
d) 65 m/s
e) need more information to calculate

Answer 8

b) 25 m/s

Question 9

A golfer drives a ball straight off the tee box (directly horizontal) that is 2 m above the fairway (assume no affect due to spin on the ball). Another golfer, at the same time the ball leaves the club, drops a ball from a height of 2 m. Which ball will hit the ground first?

a) the ball dropped by the golfer from 2m, since the ball has no horizontal velocity
b) they will both hit the ground at the same time
c) the ball struck by the golfer will make contact first

Answer 9

b) they will both hit the ground at the same time

Question 10

The division of mechanics that is most applicable to the study of the human in sport and exercise is called:

a) relatively deformable mechanics
b) deformable-body mechanics
c) quantum mechanics
d) relativistic mechanics
e) rigid-body mechanics

Answer 10

e) rigid-body mechanics

Question 11

Muscle contractions applying force to a bone are generally considered too be external forces if the system being analyzed is the movement for the whole body.

a) true
b) false

Answer 11

b) false

Question 12

Three swimmers prepare to start a race from the starting blocks, which individual will have the greatest horizontal acceleration if each force is applied directly horizontally (there are no other influences)?

a) 60 kg swimmer with a force application of 600N
b) 70kg swimmer with a force application of 500N
c) 80kg swimmer with a force application of 700N
d) none of these are correct

Answer 12

a) 60kg swimmer with a force application of 600N

Question 13

According to our class notes, performance enhancement is the primary goal in sport and exercise biomechanics, the secondary goal would be?

a) producing better equipment
b) injury prevention
c) increasing the understanding of growth and development
d) changing the approaches of learning new techniques
e) none of these are correct

Answer 13

b) injury prevention

Question 14

Which type of motion describes the flight of a long jumper’s centre of gravity, after they leave the takeoff board and sail in an arc toward the landing pit?

a) linear motion
b) curvilinear motion
c) angular motion
d) rectangular motion
e) rectangular motion

Answer 14

b) curvilinear motion

Question 15

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

a) action-reaction
b) acceleration
c) inertia
d) gravity
e) amplification

Answer 15

a) action-reaction

Question 16

Which of the following statements is true of the amount of horizontal force required to start in motion an object sitting on a horizontal surface?

a) it must be greater
b) it must be greater than the coefficient of static friction
c) it must be greater than the maximum kinetic friction of force
d) it must be greater than the maximum static friction of force
e) none of these are correct

Answer 16

d) if must be greater than the maximum static friction force

Question 17

A sprinter starts from the blocks and drives out of the blocks on the gun and reaches a maximum velocity of 11 m/s in 6 seconds. What is the average acceleration for this person during this time period?

a) 0.55 m/s2
b) 1.8 m/s2
c) 3.0 m/s2
d) 11.0 m/s2
e) none of these are correct

Answer 17

b) 1.8 m/s2

Question 18

As the surface area of two objects is contact increases, what happens to the force of the friction?

a) it increases
b) it decreases
c) it remains constant
d) it disappears
e) this depends on the weight of the object

Answer 18

c) it remains constant

Question 19

How high will a person jump, if they have an initial velocity of 2.8 m/s? Select the best answer.

a) 0.14 m
b) 0.29
c) 0.40 m
d) 0.80 m
e) none of the above

Answer 19

c) 0.40 m

Question 20

When a human body is airborne (e.g. when a person leaps through the air):

a) movement of the arms and legs will not influences the flight path of the centre of gravity
b) all of these are correct
c) none of these are correct
d) the body’s centre of gravity follows a parabolic flight path
e) we generally don’t consider air resistance as influencing the flight path of the centre of gravity

Answer 20

b) all of these are correct

Question 21

The person in the picture is moving the sled to the right. What are the forces acting on the sled (give a name for the forces) and in what directions do they act (right, left, up, down)? We will say that the sled is moving slowly, so we will ignore the effect of air resistance.
guy pushing a football like weight to the right of the screen*

Answer 21

forces of friction, left

normal force and weight force (gravity),down

propulsive force, right

Question 22

The coefficient of dynamic friction between the grass and a 200 kg football blocking sled is 0.20. 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? Pick the closest answer.

a) 40N
b) 20N
c) 392N
d) 60N
e) 196N

Answer 22

c) 392N

Question 23

Two basketball players are jumping for a rebound after the ball hits the hoop and bounces upward. What can the basketball player’s do to maximize their jump and reach height as they attempt to knock the ball away from the opponent. Please give a reason why your suggestion would be helpful to the player. Explain your answer.

Answer 23

They would want to try to manipulate their COG so they can get a higher jump. To do this is would be helpful to lift one arm up instead of both, this way the whole body is reaching up through that one arm and you will jump higher. They can also bend their knees and swing their arms to get a faster velocity going straight up

Question 24

A 90 kg hockey player skating with a velocity of 15 m/s is travelling down the ice. This player collides with another player with a mass of 80 kg and a velocity of 16 m/s going in the opposite direction. If these two players stuck together after the collision, what is the resultant momentum of the two players?

a) 1 kg.m/s in the 90kg player’s original direction
b) 70 kg.m/s in the 90kg player’s original direction
c) 10 kg.m/s in the 80kg player’s original direction
d) 115 kg.m/s in the 80kg player’s original direction
e) none of these are correct

Answer 24

b) 70 kg.m/s in the 90kg player’s original direction

Question 25

Mass is an important quantity of kinetics because is quantifies:

a) the rate of change of motion of a body
b) the quality of matter in a body
c) the net force acting on a body
d) the inertia of a body
e) none of these are correct

Answer 25

d) the inertia of a body

Question 26

A 90 kg weightlifter exerts a 1000 N force upward against a 50 kg barbell. How large is the net vertical force acting on the barbell? (pick the closest correct answer).

a) 1050N upward
b) 510N upward
c) 490N upward
d) 950N upward
e) 1490N upward

Answer 26

b) 510N upward

Question 27

Concurrent forces are forces that:

a) act at the same pint and have the same line of action
b) act at the same point and have the same magnitude of application
c) act through the same axis of an o object
d) act at the same points but in different directions
e) have the same magnitude and direction

Answer 27

d) act at the same point but in different directions

Question 28

A weightlifter lifts a 245 lb barbell. How much does this barbell weigh in Newtons? Conversions: 1 kg = 2.2 lb; 1 lb = 0.45 kg. (pick the closest answer)

a) 250N
b) 5290N
c) 110N
d) 1090N
e) 2403N

Answer 28

d) 1090N

Question 29

A research paper indicates that they have used a strain gauge for the measurement data, what would a strain gauge measure:

a) the joint angle of a limb
b) the change in shape of an object as a force
c) group reaction forces in three direction
d) muscle activity during movement
e) none of these are correct

Answer 29

b) the change in shape of an object as a force

Question 30

You are coaching a gymnast on a vault where they run, make contact with the vault and propel themselves into the air. Increasing her vertical velocity at take-off from the vault will __________ her flight time and __________ her flight distance (assuming no change in the horizontal velocity).

a) increase; decrease
b) increase; increase
c) decrease; increase
d) decrease; decrease

Answer 30

b) increase; increase

Question 31

What is the distance of the jump if a long jumper has a flight time of 0.8 seconds and an initial horizontal velocity 6 m/s? Assume no other forces act on the jumper and the takeoff and landing heights are the same.

a) 0.13m
b) 4.8m
c) 6.0m
d) 7.5m
e) none of the above

Answer 31

b) 4.8m

Question 32

Biomechanics can involve analysis of kinematic aspects of movement and kinetic factors that affect movement. Which of the following would not be involved in a kinematic description of a tennis serve?

a) angular velocity
b) linear velocity
c) force of rotator cuff muscles
d) angular acceleration
e) only statements labeled c and d are correct
f) all of these could be involved in kinematic analysis

Answer 32

c) force of rotator cuff muscles

Question 33

Analysis of long jump in track and field it becomes evident that the most important factor for achieving a long jumps is:

a) vertical velocity to extend the time of flight
b) high run up velocity that is transferred into horizontal velocity during the flight
c) a combination of statements labeled a and b, b being of greater importance
d) a high run up velocity and a take-off angle of 55 degrees to the horizontal
e) none of these are correct

Answer 33

c) a combination of statements labeled a and b, b being of greater importance

Question 34

What is the mass of a basketball player that weighs 1100N?

a) 1100kg
b) 100kg
c) 98kg
d) 112kg
e) none of these are correct

Answer 34

d) 112kg

Question 35

Electromyography (EMG):

a) sis a measure of the joint angle of a limb
b) measures the change in shape of an object as a force
c) measures direction of force produced by a muscle
d) is a measure of muscle activity during contraction or movement
e) none of these are correct

Answer 35

d) is a measure of muscle activity during contraction or movement