Final answer:
The force of friction experienced by the combined system of the person and object is c. 30 N, and a force of 100 N needs to be applied to accelerate a 5-kg object at 20 m/s².
Step-by-step explanation:
Understanding Forces and Acceleration
To determine the force of friction experienced by a system, we can use Newton's second law of motion. Newton's law states that the force is equal to mass times acceleration (F=ma). For a person weighing 55 kg pushing a 10-kg object with a force of 160 N and accelerating at 2 m/s², the total force exerted (including friction) is the sum of the force due to acceleration and the applied force.
The total mass of the system is 55 kg + 10 kg = 65 kg. Using Newton's second law: F=ma, the force due to acceleration would be F = 65 kg × 2 m/s² = 130 N. Therefore, the net force is the applied force minus the force due to acceleration: 160 N - 130 N = 30 N. This is the force of friction since it opposes the motion.
For the second scenario, to apply a force sufficient for a 5-kg object to accelerate at 20 m/s², we also apply Newton's second law. Thus, F = 5 kg × 20 m/s² = 100 N.
In conclusion, the correct options are:
- The force of friction experienced by the system is 30 N.
- The force needed to be applied to a 5-kg object to accelerate at 20 m/s² is 100 N.