measurements of the static hysteresis curve obtained by plot-
The dynamics of a collision between a ball and another
object can be determined, in principle, from the initial con-
ditions and the functional form of the force acting on the
ball. If the collision is elastic, then the force, F, acting on a
ball during the collision is given approximately by Hooke’s
law, F5kx, where x is the ball compression. The collision
can then be modeled as one between two springs.1 The
spherical geometry introduces a complication that was first
analyzed by Hertz2 for a force law of the form F5kx3/2. If
the collision is inelastic, then the relevant force law is gen-
erally an unknown function of the properties of the colliding
objects. The force law is, in fact, often irrelevant since most
problems of this type are cast in the form of conservation
equations describing conditions before and after the colli-
sion. However, a measurement of the force provides useful
information on the behavior of the objects during the colli-
sion, on the duration of the collision and on the elastic prop-
erties of the objects.
The collision of a ball always involves some loss of en-
ergy. For example, if a ball of mass m is dropped from a
height h1 onto a surface and it rebounds to a height h2 , then
the loss of energy is mg(h12h2). The energy loss can be
expressed in terms of the coefficient of restitution, e, defined
in the case of a rigid surface by e5v2 /v15Ah2 /h1, where
v1 is the incident speed of the ball and v2 is the rebound
speed. The coefficient of restitution ~COR! has been mea-
sured for many objects and surfaces, but very little informa-
tion is available on the energy loss process itself or on the
force acting on a colliding ball. For example, the energy may
be dissipated in the ball during the collision as a result of
internal friction, or energy may be lost as a result of a per-
manent deformation of the ball or the surface. Alternatively,
energy may be stored in the ball as a result of its compres-
sion and subsequently dissipated after the rebound either in
internal modes of oscillation or by a slow recovery of the
ball to its original shape. A review of head-on collisions
between solid metal spheres was presented 40 years ago in
this journal by Barnes.2,3 Since that time, there have been
many other articles on colliding balls,4,5 but only one6 in-
cluded force wave forms.
The energy loss can be predicted approximately from
measurements of the static hysteresis curve obtained by plot-The dynamics of a collision between a ball and anotherobject can be determined, in principle, from the initial con-ditions and the functional form of the force acting on theball. If the collision is elastic, then the force, F, acting on aball during the collision is given approximately by Hooke’slaw, F5kx, where x is the ball compression. The collisioncan then be modeled as one between two springs.1 Thespherical geometry introduces a complication that was firstanalyzed by Hertz2 for a force law of the form F5kx3/2. Ifthe collision is inelastic, then the relevant force law is gen-erally an unknown function of the properties of the collidingobjects. The force law is, in fact, often irrelevant since mostproblems of this type are cast in the form of conservationequations describing conditions before and after the colli-sion. However, a measurement of the force provides usefulinformation on the behavior of the objects during the colli-sion, on the duration of the collision and on the elastic prop-erties of the objects.The collision of a ball always involves some loss of en-ergy. For example, if a ball of mass m is dropped from aheight h1 onto a surface and it rebounds to a height h2 , thenthe loss of energy is mg(h12h2). The energy loss can beexpressed in terms of the coefficient of restitution, e, definedin the case of a rigid surface by e5v2 /v15Ah2 /h1, wherev1 เป็นความเร็วในการแก้ไขปัญหาของลูก และ v2 เป็นการตอบสนองความเร็วของ สัมประสิทธิ์ของ restitution ~ COR การไฟฟ้านครหลวง-หลากหลายวัตถุมาก และพื้นผิว แต่เล็ก informa-สเตรชันมีการสูญเสียพลังงานเอง หรือในการแรงที่กระทำบนลูกชน ตัวอย่าง พลังงานอาจdissipated ในลูกบอลในระหว่างการชนกันเป็นผลมาจากแรงเสียดทานภายใน หรือพลังงานอาจหายไปเป็นผลมาจากการต่อ-แมพ manent ของลูกหรือพื้นผิว หรือพลังงานอาจถูกเก็บไว้ในลูกจาก compres เป็น-น และต่อมา dissipated หลังจากการตอบสนองอย่างใดอย่างหนึ่งในภายในโหมด ของการสั่น หรือการฟื้นตัวที่ช้าของการลูกบอลรูปเดิม การตรวจสอบของตาม head-onระหว่างทรงกลมโลหะแข็งถูกเสนอเมื่อ 40 ปีที่ผ่านมาในสมุดรายวันนี้ โดย Barnes.2,3 ตั้งแต่ นั้น มีการในบทความอื่น ๆ เกี่ยวกับชนลูก one6 4, 5 แต่เพียงในรูปแบบคลื่นแรง cludedว่าสามารถทำนายการสูญเสียพลังงานประมาณจาก
การแปล กรุณารอสักครู่..