For an object to remain at rest, which of the following must be true? question 2 options: the foreces on it are balanced , there is not friction , gravity does not act on it , the onject has no mass.

For an object to remain at rest, the forces acting on the object are balanced.

According Newton's second law of motion, when a force is applied on an object, the object tends to move in the direction of the applied force. This occurs when there is unbalanced force acting on the object.

F = ma

However, if the forces acting on the object is balanced, the object remains at rest or in equilibrium position.

Thus, we can conclude that, for an object to remain at rest, the forces acting on the object are balanced.

Learn more here:link

a: 45.9 meters

b: 4.29 seconds

step-by-step explanation:

a: h(t)=1/2(-9.8)(3)^2+0(3)+90

h(t)=-4.9(3)^2+90

h(t)=-44.1+90

h(t)=45.9 meters

b: 0=1/2(-9.8)(t^2)+0t+90

0=-4.9t^2+90

-90=-4.9t^2

18.37=t^2

t=4.29 seconds

in the second question, the numbers aren't exact, but they're a close approximation.