A golf ball 2 includes a core 4 and a cover 6. A value V calculated by the following mathematical formula is equal to or less than 1080 Hz.

V=NF(2)22/3*NF(2)1

In the mathematical formula, NF(2)1 represents a secondary natural frequency of the core 4, and NF(2)2 represents a secondary natural frequency of the golf ball 2. A difference (H1sH1o) between a Shore C hardness H1s at a surface of the core 4 and a Shore C hardness H1o at a central point of the core 4 is equal to or greater than 10. An amount of compressive deformation Df1 of the core 4 is equal to or greater than 4.1 mm.

An ultra-low compression golf ball is disclosed herein. The core preferably has a PGA compression less than 30. The mantle layer and cover have approximately the same thickness. The cover comprises a thermoplastic polyurethane material and has a specific gravity greater than the core and mantle layer. The golf ball has a PGA compression less than 75 and a COR of at least 0.780.

Synergistic pairing of golf clubs with golf balls both with improved aerodynamic properties to help improve the performance of both. In an example, a golf club has a golf club head; a grip; and a shaft having a tip end and a butt end. The golf club head is coupled to the shaft at the tip end, and the grip is coupled to the shaft at the butt end. The golf ball has at least a core and a cover having a plurality of dimples arranged in a dimple pattern.

Synergistic pairing of golf clubs with golf balls both with improved aerodynamic properties to help improve the performance of both. In an example, a golf club has a golf club head; a grip; and a shaft having a tip end and a butt end. The golf club head is coupled to the shaft at the tip end, and the grip is coupled to the shaft at the butt end. The golf ball has at least a core and a cover having a plurality of dimples arranged in a dimple pattern.

An ultra-low compression three-piece golf ball is disclosed herein. The core preferably has a PGA compression less than 30. The mantle layer and cover have approximately the same thickness. The cover comprises a thermoplastic polyurethane material and has a specific gravity greater than the core and mantle layer. The golf ball has a PGA compression less than 75 and a COR of at least 0.780.

An object of the present invention is to provide a golf ball excellent in flying performance, in particular, to provide a golf ball traveling a great flight distance. The present invention provides a golf ball having a spherical core and at least one cover layer covering the spherical core, wherein the spherical core is formed from a rubber composition containing (a) a base rubber, (b) an ,-unsaturated carboxylic acid having 3 to 8 carbon atoms and/or a metal salt thereof as a co-crosslinking agent, (c) a crosslinking initiator, and (d1) an aromatic carboxylic acid or (d2) an aromatic carboxylic acid salt, provided that the rubber composition further contains (e) a metal compound in the case of containing only (b) the ,-unsaturated carboxylic acid having 3 to 8 carbon atoms as the co-crosslinking agent.

A golf ball has a large number of dimples on a surface thereof. The golf ball meets the following mathematical formula (I): 1.320L11.420 (I), where L1 represents a ratio of a lift coefficient CL1 which is measured under conditions of a Reynolds number of 1.29010.sup.5 and a spin rate of 2820 rpm, relative to a lift coefficient CL2 which is measured under conditions of a Reynolds number of 1.29010.sup.5 and a spin rate of 1740 rpm.

A golf ball 2 includes a core 4, a mid layer 6 and a cover 8. The golf ball 2 further includes a large number of dimples 10 on a surface thereof. The surface has a northern hemisphere N and a southern hemisphere S. Each of the hemispheres has a high-latitude region 14, a mid-latitude region 18 and a low-latitude region 16. The number of planes that can divide a dimple pattern of the hemisphere so that divided dimple patterns are mirror symmetry to each other is one. Neither a dimple pattern of the high-latitude region 14 nor a dimple pattern of the low-latitude region 16 is rotationally symmetrical. A product THm of a thickness and a hardness for the mid layer 6, and a product THc of a thickness and a hardness for the cover 8 satisfy the following mathematical formula.
THcTHm50

The present invention provides a golf ball in which dimples are formed on a ball surface, wherein when edge angles at points where depths are 10%, 20%, and 30% in a cross-section of one dimple are denoted as ED1, ED2, and ED3, respectively, dimples with a cross-sectional shape satisfying the following condition (1):

[00001]$\begin{array}{cc}\mathrm{ED}1<\mathrm{ED}2>\mathrm{ED}3& \left(1\right)\end{array}$

account for at least 10% of a total number of the dimples, and further a ratio A1 of a lift coefficient at a Reynolds number of 218,000 and a spin rate of 2,800 rpm to a drag coefficient, a ratio A2 of a lift coefficient at a Reynolds number of 184,000 and a spin rate of 2,900 rpm to a drag coefficient, and a ratio A3 of a lift coefficient at a Reynolds number of 158,000 and a spin rate of 3,100 rpm to a drag coefficient are optimized.

In a golf ball including a core, an intermediate layer, and a cover, the relationship of the surface hardness between an intermediate layer-encased sphere and the ball satisfies a predetermined relational expression, and with an initial velocity of the ball and a deflection under a predetermined load applied to the ball optimized, and letting a value of (initial velocity of coreweight of core) be Ciw, a value of [(initial velocity of intermediate layer-encased sphereinitial velocity of core)(weight of intermediate layer-encased sphereweight of core)] be Miw, and a value of [(initial velocity of ballinitial velocity of intermediate layer-encased sphere)(weight of ballweight of intermediate layer-encased sphere)] be CViw, the expression of Ciw+Miw+CViw is optimized, and lift and drag coefficients at predetermined Reynolds numbers and spin rates of dimples are set to predetermined ranges.