(c) It may deform a fixed body against its external supports and resistances.  In making impact tests in the laboratory the test specimen is in reality in the nature of a cushion between two impacting bodies, namely, the striking weight and the base of the machine.  It is important that the mass of this base be sufficiently great that its relative velocity to that of the common centre of gravity of itself and the striking weight may be disregarded.

(d) It may deform the struck body as a whole against the resisting stresses developed by its own inertia, as, for example, when a baseball bat is broken by striking the ball.

|------------------------------------------------------

-|
|                        TABLE X                        |
|-------------------------------------------------------|
| RESULTS OF IMPACT BENDING TESTS ON SMALL CLEAR BEAMS  |
|            OF 34 WOODS IN GREEN CONDITION             |
|               (Forest Service Cir. 213)               |
|-------------------------------------------------------|
|                   |   Fibre   |            | Work in  |
|    COMMON NAME    | stress at | Modulus of | bending  |
|    OF SPECIES     |  elastic  | elasticity |    to    |
|                   |   limit   |            | elastic  |
|                   |           |            |  limit   |
|-------------------+-----------+------------+----------|
|                   |           |            | In.-lbs. |
|                   | Lbs. per  |  Lbs. per  | per cu.  |
|                   | sq. in.   |  sq. in.   | inch     |
|                   |           |            |          |
|    Hardwoods      |           |            |          |
|                   |           |            |          |
| Ash, black        |    7,840  |    955,000 |    3.69  |
|   white           |   11,710  |  1,564,000 |    4.93  |
| Basswood          |    5,480  |    917,000 |    1.84  |
| Beech             |   11,760  |  1,501,000 |    5.10  |
| Birch, yellow     |   11,080  |  1,812,000 |    3.79  |
| Elm, rock         |   12,090  |  1,367,000 |    6.52  |
|   slippery        |   11,700  |  1,569,000 |    4.86  |
|   white           |    9,910  |  1,138,000 |    4.82  |
| Hackberry         |   10,420  |  1,398,000 |    4.48  |
| Locust, honey     |   13,460  |  2,114,000 |    4.76  |
| Maple, red        |   11,670  |  1,411,000 |    5.45  |
|   sugar           |   11,680  |  1,680,000 |    4.55  |
| Oak, post         |   11,260  |  1,596,000 |    4.41  |
|   red             |   10,580  |  1,506,000 |    4.16  |
|   swamp white     |   13,280  |  2,048,000 |    4.79  |
|   white           |    9,860  |  1,414,000 |    3.84  |
|   yellow          |   10,840  |  1,479,000 |    4.44  |
| Osage orange      |   15,520  |  1,498,000 |    8.92  |
| Sycamore          |    8,180  |  1,165,000 |    3.22  |
| Tupelo            |    7,650  |  1,310,000 |    2.49  |
|                   |           |            |          |
|    Conifers       |           |            |          |