Question

Austin (58 kg body mass) is recovering from knee surgery and is doing testing to be cleared to return to sport. One of the evaluations is a vertical jump on a force plate which gives ground reaction force. The data show that they stood motionless for 1 s then initiated the counter-movement jump. What was the vertical ground reaction force reduced to?

1) 77.9
2) 58
3) 1
4) Cannot be determined

Answer 1

The correct vertical ground reaction force for someone with a mass of 58 kg standing motionless should be approximately 568.4 N, obtained using the equation F = m * g. The given options do not include this value; hence, the correct answer cannot be determined from the options provided.

Step-by-step explanation:

The student is asking about the vertical ground reaction force measured by a force plate during a counter-movement jump performed by someone recovering from knee surgery. When motionless on the force plate, the ground reaction force should equal the weight of the individual due to gravity. To calculate this force, we use the equation F = m * g”, where F is the force, m is the mass, and g is the acceleration due to gravity (approximately 9.8 m/s²). For Austin, who has a mass of 58 kg, the vertical ground reaction force when standing motionless would be 58 kg * 9.8 m/s², which amounts to approximately 568.4 N (rounded to 569 N when considering significant figures). Therefore, none of the provided options (77.9, 58, 1) represents the correct vertical ground reaction force while Austin is motionless, and the correct answer is (4) Cannot be determined from the given options.