Final answer:
The net external force on the 24 kg mower is responsible for its acceleration. Newton's second law allows us to calculate the acceleration by dividing the net force by the mass of the mower, resulting in an acceleration of 2.125 m/s².
Step-by-step explanation:
The net external force on a 24 kg mower is responsible for the mower's acceleration. According to Newton's second law of motion, the net force acting on an object is equal to the mass of the object multiplied by its acceleration (F = ma). In the given scenario, a net external force of 51 N is exerted on the mower, and if we assume no other forces are acting (like air resistance), the acceleration can be calculated using the formula a = F/m, where F is the net force and m is the mass of the mower. Hence, the mower's acceleration would be a = 51 N / 24 kg = 2.125 m/s2. The acceleration is in the same direction as the net external force, which in this case is parallel to the ground.