Understanding Exit Velocity
Exit velocity is the speed at which the baseball leaves the bat after contact. This metric is crucial in baseball for evaluating hitting performance and is influenced by both the pitch speed and the bat speed.
Formula
The exit velocity formula incorporates the coefficient of restitution (material factor) for the bat:
[\text{Exit Velocity} = \text{MF} \times \text{Pitch Speed} + (1 + \text{MF}) \times \text{Bat Speed}]
For wooden bats, the material factor (MF) is 0.2.
Example
Given the following values:
- Material Factor (MF) = 0.2
- Pitch Speed = 90 mph
- Bat Speed = 80 mph
Calculation:
[\text{Exit Velocity} = 0.2 \times 90 + 1.2 \times 80]
[\text{Exit Velocity} = 18 + 96 = 114 \text{ mph}]
The baseball leaves the bat at 114 mph.
Key Factors
Bat Speed Impact: Notice that bat speed is multiplied by 1.2 (1 + MF), making it the dominant factor in determining exit velocity. A faster swing generates significantly higher exit velocity.
Pitch Speed Contribution: While pitch speed does add to exit velocity, its contribution is much smaller due to the 0.2 multiplier.
Material Properties: Different bat materials (wood, aluminum, composite) have different coefficients of restitution, affecting how energy transfers during contact.