Which of these would be an example of unbalanced forces? question 7 options: 1] a dog runs at a constant velocity. 2] your coffee cup does not move from its original spot on the desk. 3] a snowball picks up speed as it rolls down the mountain. 4]you stand very still during the national anthem.

3] A snowball picks up speed as it rolls down the mountain.

Explanation:

Newton's second law states that:

where

F is the net force acting on an object

m is the mass of the object

a is the acceleration of the object

When the net force acting on the object is zero, we say  that the object is acted upon balanced forces; when the net force is non-zero, we say that unbalanced forces are acting on the object. From the formula, we see that when unbalanced forces are acting on the object, the object has an acceleration different from zero: this also means that the velocity of the object is changing.

So, we can say that if there are unbalanced forces, then the object's velocity is changing. Among the choices given, we see that velocity is changing only in options 3) (the snowball is speeding up, so it has an acceleration), while in all other cases the velocity is constant. Therefore, option 3) is the  correct one.

the answer is false. this is because for ice to melt, it requires latent heat of melting. latent heat means heat energy required to change phase without any increase in temperatures. therefore, the ice will take energy from the environment to melt hence atmospheric temperatures will reduce.