Final answer:
The normal force on an 80 kg object at rest on a horizontal surface is equal to its weight, calculated as 80 kg times the acceleration due to gravity (9.8 m/s²), which equals 784 N.
Step-by-step explanation:
To find the normal force acting on an 80 kg object, we need to consider the object at rest on a horizontal surface. In this scenario, the normal force is equal to the weight of the object if there is no other vertical force acting on the object other than gravity. The weight (W) of the object can be calculated using the formula W = mass × gravity. The mass is given as 80 kg and the acceleration due to gravity (g) is approximately 9.8 m/s². Therefore, the normal force (N) is given by:
N = mass × gravity
N = 80 kg × 9.8 m/s²
N = 784 N
The correct answer is (a) 784 N, which represents the normal force acting on the object.