";s:4:"text";s:11572:" The images also show a relatively long time with both skates in contact with the ice, as the center of mass is shifted from right to left, while the right skate pushes away. The sideways motion of the arms swinging from side to side, as in figure 3, also reduces the sideways motion of the core of the body. [9–12]). Click here to close this overlay, or press the "Escape" key on your keyboard. A typical starting sequence is illustrated in figure 2. In our efforts to find challenging, yet interesting and realistic, examples to present for physics students, we focus here on a well-known and popular sport—ice hockey—and in particular how the players are skating. A skater moving on an inside edge in a circular arc can push the centre of mass of the body towards the centre of the circle. ( Log Out / a complete stop (depending on their weights and speeds), we can still calculate In this section we discuss angular momentum skating, where the change in direction is instead provided by moving along a circular arc. As the left skate makes contact with the ice again on the outside edge, it helps pushing the body to the left. A joule is not a lot of energy. The kinetic energy lost during a stride, {\rm{\Delta }}{E}_{k,0}=(1-{\alpha }^{2}){{mv}}_{i}^{2}/2, needs to be supplied during the push-off, to allow the next stride to start with a velocity {{\bf{v}}}_{i,l}={v}_{i}(-\sin \theta ,\cos \theta ), slightly to the left. Change ), You are commenting using your Facebook account. BibTeX To find out more, see our, Browse more than 70 science journal titles, Read the very best research published in IOP journals, Read open access proceedings from science conferences worldwide, Postdoctoral Researcher and Doctoral Student, Postdoctoral Researcher and Two Doctoral Students. This paper explores the physics underlying this experience, comparing traditional hockey strides and the alternative technique, shown in figure 1, where circular arcs are used to achieve a change of direction. No additional energy is needed for the change of direction. The work required is then (1+{\alpha }^{2}){{mv}}_{i}^{2}/2, which is the sum of the work required to stop the motion in the initial direction (as seen from the skating rink) and the work to reach the full velocity in the orthogonal new direction. Number 6, 4444 Total downloads Every object in a state of uniform motion tends to remain in that state of motion unless an external … Export citation and abstract to lift an apple to the height of your waist (1 meter).
entangled and "stick" to each other during the collision. This paper applies classical mechanics to different ways of skating in ice hockey. Hayward-Ellis et al [18] analysed the 'ground reaction forces' using different arm swing techniques and found that the sideways reaction forces caused by this arm swing is comparable to the sideways force from the skates. Finally, we discuss an angular-momentum-based technique to reverse the direction of motion as fast as possible. J. Phys. If instead all kinetic energy were lost before starting the next stride, i.e. This site uses cookies. Depending on the size of the opposing player in the collision, the player that was collided with and interrupted by could fall down or be totally stopped. After the right skate leaves the ice, the body rotates to an inside edge of the left skate, which then pushes the body towards the centre of the circular arc, which is shifted to the right. We do this is an equal and opposite reaction -- each player must experience the same The speed at the beginning of each stride is denoted by vi. ahead of the Philadelphia Flyers by one goal.
Selection of screen shots from figure 1, showing the different parts of a stride, as described in section 4.
This second row of the sequence in figure 1 shows the left skate getting contact with the ice again, first on the outside edge possibly providing supporting to the right skate as the body is pushed to the left, shifting the centre of mass. The shift of the centre of mass can be achieved by expanding the legs and/or leaning more into the centre.
171 Video abstract views, 1 Erikstorpsvägen 39 F, SE 261 61 Landskrona, Sweden, 2 Tulegatan 17 A, SE 871 41 Härnösand, Sweden, 3 National Resource Centre for Physics Education, Lund University, Box 118, SE 22100 Lund, Sweden, 4 Department of Mathematics and Science Education, Kristianstad University, SE 29188 Kristianstad, Sweden. the final energy by 60 to calculate the time in seconds. momentum (mass x velocity) of both players must equal the final momentum It can also be noted that the track in figure 3 deviates from a straight line—during the last part of the stride, the skate turns slightly outwards to allow for the push to be better aligned with the gliding on the other leg, since the horizontal part of the force from the ice, is essentially perpendicular to the skating blade. For the analysis in this section, it makes no difference whether the force to shift the centre of mass comes from one skate or the other, or a combination, as the mass shifts from one skate to the other, in preparation for the next stride. In this work, we have shown how angular momentum can play a role also for forward skating. The third row in figure 1 shows the right skate making contact with the ice, and the left skate pushing it closer to the centre of the arc. Table 1 shows the different phases of a sequence of moves, connecting to the annotated sequence of screen shots in figures 6 and 7 and to the annotated track in figure 8. Figure 7 shows annotated screen shots at 0.1s intervals of the motion viewed from behind. on swings [1], drop towers [2], trampolines [3, 4] and roller coasters [4, 5]. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI. velocity player 2) = combined mass x final velocity.
You will only need to do this once. by hitting him straight on. 5 Author to whom any correspondence should be addressed. You do not need to reset your password if you login via Athens or an Institutional login. When shooting, as far as the player pulls the stick backward, half his body goes with the stick, while the other half goes forward at the same time. [6, 7]). The ice provides the centripetal force, which may be distributed on both skates. than an open ice hit.