The Force Plate, like any sensor, has a limit to how quickly it can respond to a change. If a very short impulse is applied to the force plate, it will vibrate, or ring, for a short while. That ringing can interfere with your measurement.
Revised (FP-BTA) and Go Direct Force Plate
The current version of the Force Plate (FP-BTA) and the Go Direct® Force Plate (GDX-FP) have load cells that allow you to sample at rates up to 500 Hz without noticeable interference from the ring frequency.
This means that you could bounce most sports balls (if they are heavy enough – most nerf balls, for example, are not) off of the plate and see the details of the impulse.
Original (FP-BTA) Force Plate
The original version of the Force Plate (those shipped before November 10, 2023) uses different load cells that have a ringing frequency of ~250 Hz, with a ~4 ms period. Any impulse with a duration shorter than 4 ms will only show the ringing; there is no way to resolve anything shorter than that. Even a 10 or 20 ms impulse will be distorted by the finite response time of the force place. In order to really see the structure of an impulse, the impulse should be ~200 ms or longer.
This means that you can bounce a soft, squishy ball off this older version of the force plate and see the details of the impulse, however, you can’t get useful data for the impulse of a baseball or a golf ball using this force plate.