Final answer:
An object at rest on the ground that experiences an upward force will accelerate upward. The magnitude and direction of the normal force on a resting object is equal to mg in the upward direction, opposing the force of gravity.
Step-by-step explanation:
When an object at rest on the ground experiences a force directed upward, the likely effect on the object is that it accelerates upward. This is because, according to Newton's second law of motion, a force applied to an object will cause it to accelerate in the direction of the force. Assuming there is no other force opposing this upward force (such as the force of gravity, if the net force were to be considered), the object would start moving in the upward direction. This can be further understood by considering a one-dimensional motion scenario where only vertical forces and displacement are involved, and using the concept of free-fall and the acceleration due to gravity, commonly denoted as g (9.80 m/s² towards the center of Earth).
Regarding the magnitude and direction of the normal force acting on an object at rest, the correct answer would be N=mg in the upward direction. The normal force is a contact force exerted by a surface to support the weight of the object resting on it, and it's always perpendicular to the contact surface. Therefore, on an object at rest with mass m, the normal force (N) is equal to the object's weight, which is the product of mass (m) and acceleration due to gravity (g), and it points upward, opposite to the direction of gravity.