Momentum and Energy © Pearson Education, Inc. - ppt video online download
Newt says the momentum of an object will change if and only if a net While we can show that F = MA came from the impulse relationship. Momentum 1. A freight train rolls along a track with considerable momentum. The impulse-momentum relationship is a direct result of 4. A rifle recoils while. Lesson 9: Linear Kinetics: Linear Impulse – Momentum Applications The result of this braking impulse is to decrease the horizontal velocity of the runner's . For a vertical force you must subtract the weight of the object/person before dividing by mass. The graph below shows the direct relationship between force and.
Compared with the 1-kg ball, the kg ball has the same momentum. B 5 times as much momentum. Both of the above.
Chapter 6: Momentum - ProProfs Quiz
Neither of the above. Note that momentum is proportional to speed, but kinetic energy is proportional to speed squared. Compared with the momentum given to the cannonball, the momentum of the recoiling cannon is ideally less.
B equal and opposite. Note the similarity of this with Newton's third law.
More time in the impulse that stops the ball results in less force and less ouch. D all of the above. The mass of the ball is one-tenth your mass. Compared with the speed you give to the ball, your recoil speed will ideally be one-tenth as much.
- Momentum and Energy © 2013 Pearson Education, Inc.
- Chapter 6: Momentum
- Impulse-momentum relationship is a direct result of which Newton law?
A truck at rest has no momentum at all. But if the truck is at rest and the roller skate moves, then the skate has more momentum.
Can you think of a case where a roller skate and a truck would have the same momentum? The roller skate and truck can have the same momentum if the speed of the roller skate is much greater than the speed of the truck.
8 Momentum Momentum is conserved for all collisions as long as external forces don’t interfere.
For example, a kg truck backing out of a driveway at 0. The greater the force acting on an object, the greater its change in velocity and the greater its change in momentum. A golfer teeing off and a baseball player trying for a home run do both of these things when they swing as hard as possible and follow through with their swing. A golf club that strikes a golf ball exerts zero force on the ball until it comes in contact with it.
The force increases rapidly as the ball becomes distorted. The force diminishes as the ball comes up to speed and returns to its original shape. We can use the average force to solve for the impulse on an object. A wrestler thrown to the floor extends his time of hitting the mat, spreading the impulse into a series of smaller ones as his foot, knee, hip, ribs, and shoulder successively hit the mat. The boxer moves away from the punch.
The boxer moves toward the punch. The shorter time hitting the sidewalk results in a greater stopping force. The safety net reduces the stopping force on a fallen acrobat by substantially increasing the time interval of the contact. When a dish falls, will the impulse be less if it lands on a carpet than if it lands on a hard floor? The impulse would be the same for either surface because the same momentum change occurs for each. It is the force that is less for the impulse on the carpet because of the greater time of momentum change.
You provide an impulse to reduce its momentum to zero. If you throw the pot upward again, you have to provide additional impulse. If it bounces from your head, you may be in more serious trouble because impulses are greater when an object bounces.
The increased impulse is supplied by your head if the pot bounces. Her hand bounces back, yielding as much as twice the impulse to the bricks. Pelton designed a curve-shaped paddle that caused the incoming water to make a U-turn upon impact. Molecular forces within a basketball have no effect on the momentum of the basketball. 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. 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. 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.