1.
What are the four kinematic variables?
Explanation
The four kinematic variables are position, displacement, velocity, and acceleration. These variables are used to describe the motion of an object. Position refers to the location of an object in space, displacement is the change in position, velocity is the rate at which the position changes, and acceleration is the rate at which the velocity changes.
2.
There is more displacement during which phase of walking?
Correct Answer
C. Swing phase
Explanation
During the swing phase of walking, there is more displacement. This phase occurs when the foot is off the ground and swinging forward to take the next step. It involves the leg and foot moving through the air, allowing for a greater range of motion and displacement compared to the stance phase, where the foot is in contact with the ground. The flight phase is not a recognized phase of walking, so it does not contribute to displacement.
3.
On an angular displacement chart that displays positive and negative values for hip, knee, and ankle movements, what do the positive values indicate?
Correct Answer
B. Plantar flexion
Explanation
Positive values on an angular displacement chart for hip, knee, and ankle movements indicate plantar flexion. Plantar flexion refers to the movement of pointing the foot downwards, away from the body. In this context, positive values represent the degree of plantar flexion achieved during the movement.
4.
If velocity is constant, acceleration is
Correct Answer
A. Zero
Explanation
If the velocity is constant, it means that the object is moving at a steady speed in a straight line without changing its direction. In this case, the object is not accelerating because acceleration is the rate at which velocity changes over time. Since the velocity is not changing, the acceleration is zero.
5.
When do the increases in stride length occur?
Correct Answer
C. Before the increase in stride rate with increased running speed
Explanation
The increases in stride length occur before the increase in stride rate with increased running speed. This means that when a person starts running faster, they first increase their stride length, and then they increase their stride rate.
6.
The ACL prevents what kind of displacement relative to the femur?
Correct Answer
B. Anterior tibial displacement
Explanation
The ACL (anterior cruciate ligament) prevents anterior tibial displacement. This means that it prevents the tibia (shinbone) from moving forward relative to the femur (thighbone). The ACL is an important stabilizing ligament in the knee joint, and its main function is to prevent excessive forward movement of the tibia, particularly during activities such as running, jumping, and pivoting. Injury to the ACL can result in instability and a feeling of the knee "giving way" during these movements.
7.
A vertical impulse of 500 Ns is applied to a 60 kg person during the stance phase of running. The person's initial velocity at heel contact was -2.0m/s. What is the final vertical velocity at toe-off?
Correct Answer
D. 6.3
Explanation
During the stance phase of running, a vertical impulse is applied to the person. This impulse causes a change in the person's momentum. Using the principle of conservation of momentum, we can calculate the final vertical velocity at toe-off. The initial momentum is calculated by multiplying the person's mass (60 kg) by their initial velocity (-2.0 m/s). The impulse (500 Ns) is equal to the change in momentum, which can be calculated by subtracting the initial momentum from the final momentum. Dividing this impulse by the person's mass gives us the change in velocity. Adding this change in velocity to the initial velocity gives us the final vertical velocity at toe-off, which is 6.3 m/s.
8.
What is the formula for Kinetic Energy?
Correct Answer
KE=1/2mv^2
Explanation
The formula for kinetic energy is KE=1/2mv^2. This formula represents the relationship between an object's mass (m) and its velocity (v) in determining its kinetic energy. The equation shows that kinetic energy is directly proportional to the square of the object's velocity and half of its mass. This means that as either the mass or velocity of an object increases, its kinetic energy will also increase. Conversely, if either the mass or velocity decreases, the kinetic energy will decrease.
9.
Law of Inertia states
Correct Answer
A. An object will remain stationary or move with constant velocity until an external force is applied to the object
Explanation
The Law of Inertia states that an object will remain stationary or move with constant velocity until an external force is applied to the object. This means that an object will continue to stay at rest or move in a straight line at a constant speed unless acted upon by an external force. Once a force is applied, the object will accelerate in the direction of the force, at a rate inversely proportional to its mass.
10.
Momentum depends on the _____ and ______ of an object
Correct Answer
mass, velocity
velocity, mass
Explanation
Momentum is a property of an object that depends on both its mass and velocity. Mass refers to the amount of matter in an object, while velocity refers to the speed and direction of its motion. The greater the mass of an object, the greater its momentum will be. Similarly, the greater the velocity of an object, the greater its momentum will be. Therefore, both mass and velocity play a crucial role in determining the momentum of an object.
11.
What is the impulse momentum equation?
Correct Answer
F*t=m(vf-vi)
Explanation
The impulse momentum equation, F*t=m(vf-vi), relates the change in momentum of an object to the force applied to it and the time over which the force is applied. It states that the product of the force and the time it acts on an object is equal to the change in momentum of the object, which is the mass of the object multiplied by the final velocity minus the initial velocity. This equation is derived from Newton's second law of motion, which states that the force acting on an object is equal to the rate of change of its momentum.
12.
When impulse and momentum are in opposite directions, momentum is
Correct Answer
B. Decreased
Explanation
When impulse and momentum are in opposite directions, it means that the force applied to an object is acting against its motion. This results in a decrease in the object's momentum. The impulse-momentum relationship states that the change in momentum of an object is equal to the impulse applied to it. Since impulse is the product of force and time, when the force is in the opposite direction of the momentum, it will cause a decrease in the object's momentum. Therefore, the correct answer is decreased.
13.
Braking impulses _______ horizontal momentum.
Correct Answer
reduces
Explanation
Braking impulses act in the opposite direction to the horizontal momentum of an object. By applying a braking force, the object's momentum is gradually decreased, resulting in a reduction in its horizontal motion. Therefore, braking impulses reduce the horizontal momentum of an object.
14.
Which body segment has the largest moment of inertia?
Correct Answer
C. Trunk
Explanation
The trunk has the largest moment of inertia because it is the largest and heaviest body segment. Moment of inertia is a measure of an object's resistance to changes in its rotational motion, and it depends on both the mass and distribution of mass within the object. Since the trunk is larger and contains a significant amount of mass, it has a larger moment of inertia compared to the other body segments listed.
15.
With increased knee flexion, torque increases because
Correct Answer
C. Lever arm distance increases
Explanation
With increased knee flexion, the lever arm distance between the point of force application and the axis of rotation (knee joint) increases. This means that the force applied to the knee joint is applied at a greater distance from the axis of rotation, resulting in a larger lever arm. According to the principle of torque, torque is directly proportional to the lever arm distance. Therefore, as the lever arm distance increases, the torque also increases.