The momentum of a 4-kg dog running with a velocity of m/s is. 6 m/s2; The impulse-momentum relationship is a direct result of Newton's. First law. E) none of the above 4) The impulse-momentum relationship is a direct result of A) Newton's 1st law. B) Newton's 2nd law. C) Newton's 3rd law. D) Newton's law . 1) Which of the following has the largest momentum relative to the Earth? 4) The impulse-momentum relationship is a direct result of D) Newton's 4th law.
A collision is considered elastic if a. There is no lasting deformation b. After the collision, the objects have the same shape as before the collision e. All of the above 8. A freight train rolls along a track with considerable momentum.
If it were to roll at the same speed but had twice as much mass, its momentum would be a. A billiard ball collides with a stationary identical billiard ball in an elastic head-on collision. After the collision, which of the following is true of the first ball? It maintains its initial velocity b. It has one-half its initial velocity c. It comes to rest d. It moves in the opposite direction If a force is exerted on an object, which statement is true?
Describe a case where a roller skate and a truck would have the same momentum.
What are momentum and impulse?
When a dish falls, will the impulse be less if it lands on a carpet than if it lands on a hard floor? One glider is loaded so it has three times the mass of another glider.
The loaded glider is initially at rest. The load-velocity relationship assumes that the movement velocity is the maximum possible for the given load. This relationship between force and velocity is what may have prompted some to suggest that the voluntary muscle action should be carried out over a s period so that the velocity is low, thereby increasing force Wescott, Impulse and momentum The relationship between force and velocity for a constant mass such as is encountered in free-weight training is given in the relationship between impulse and momentum.
A constant mass under the influence of a force can be expressed with Newton's second law represented by equation 1. In the above case, the acceleration a experienced by an object is directly proportional to the force impressed F and inversely proportional to its mass m.
Since acceleration is the first derivative d of velocity with respect to time, the equation can also be written to reflect the first derivative with respect to time rate of change in the quantity mv. In such a case linear momentum L is expressed as equation 2. When a force acts upon the object from a time period from t1 to t2, equation 1 can be integrated in time to obtain equation 3. Equation 3 defines linear impulse Iand is equal to the change in linear momentum, as shown in equation 4.
As mass is constant during free-weight resistance training, a greater impulse will result in a greater velocity. In human movement, force is required first to maintain static equilibrium and second to generate acceleration. The force required to maintain static equilibrium is equal to an object's mass multiplied by gravitational acceleration.
Additional force results in acceleration of a mass or a change in momentum. These components of acceleration are described in equation 5: Therefore, as generation of force greater than the weight of the resistance increases i. As velocity approaches zero, propulsive force approaches zero, therefore slow moving objects only require force approximately equal to the weight of the resistance.Angular Motion and Torque
The slower the intended velocity, the closer the force expressed comes to equalling the linear inertia of the load i. From Equation 1force is inversely proportional to time. That is, to perform a movement in a shorter period of time, greater force must be generated.
What are momentum and impulse? (article) | Khan Academy
Arguments have been made that the muscle tension will be constant through the given range of motion, and thus provide optimum stimulation throughout such range Wescott, This statement has not been experimentally verified and unfortunately neglects the changes in moment arm and muscle length which ultimately change the muscle force regardless of speed of action.
This argument does, however, have some factual basis, as the impulse increases as time increases Equation 4in the case of maximal effort actions. In the case of PS, increasing time decreases force, and excessive time duration will not maximize impulse.
Arguments for purposefully slow PS training Muscle force: While PS proponents vary in their reasoning for suggesting this method, the basic premise is that when the weight is moving quickly, the muscles will not be able to exert as much force and thus the training effect will be diminished Brzycki, ; Wescott, While true that the muscles will not produce as much force at the higher velocities during maximum effort velocity-controlled actions, the previous statement ignores the requisite force to initiate high velocity movements for a given load in an isoinertial condition.
In addition, the aforementioned F-V relationship was derived under conditions of maximal acceleration maximal voluntary muscle activationand thus differs from intentionally slow movements.
An attempt to reduce the speed of motion subsequently reduces the force expressed Keogh et al. Modifications to any one of these metabolic factors during exercise may alter signal transduction pathways and hence modify gene transcription for muscle growth Rennie et al. Potential strength adaptations due to acute metabolic stimuli have recently been reviewed elsewhere Crewther et al.
The metabolic hypothesis has not yet been examined in conjunction with PS training studies; therefore these ideas are currently speculative for this type of training. Movements performed at low velocities prolong the time of contraction in each repetition for a given range of motion time-under-tension; TUT. Proponents of PS training regard this increased time as a positive characteristic to stimulate training adaptation Wescott et al.
TUT can be considered a manner by which to prescribe a dose of resistance exercise Tran and Docherty,which is crucial as the optimal dose for weight training is subject to tremendous debate Carpinelli and Otto, ; Stone et al. PS advocates suggest that this time dose or TUT is of greater importance than the actual load lifted, which could be related to the fact that perceived effort in PS and normal training session have been shown to be similar Egan et al. This rationale originates from the hypothesis of a direct relationship between the duration of contraction and metabolic stimulus, but this hypothesis has not been supported in studies examining PS exercise Gentil et al.
A potential caveat of increased TUT is that the load must be decreased to perform a successful s concentric contraction as compared to a maximal acceleration repetition i.
This is concerning as the load, or mechanical stimuli, has been suggested to be of critical importance for inducing adaptation Dudley et al. However, the reduced load advocated by PS might be less effective for hypertrophy due to the load constraints.
This reduction in load is seen by PS advocates as inconsequential to the ultimate physiological effects. However, a basic premise of tissue adaptation i.
Wolff's and Davis' Laws Biewener and Bertram, is that a minimum threshold of force is required to elicit adaptation. The notion that load is peripheral in its importance is in direct opposition to other authors' demonstrating the magnitude of mechanical stress i.
Please note that although related, load and muscle force are not equal, as propulsive forces can differ.