1. Answer: Option C
Displacement is a vector quantity. It has both magnitude as well as direction. Hence, it can be positive, zero or negative. In the given question, downward direction is taken as negative. This we have come to know from the downward acceleration 
. The negative sign indicates that downward direction is considered negative.
Now, since the object is dropped from the top. The displacement should be negative, because the negative represent a downward direction.
2. Answer: velocity
The truck is travelling at 30 mph to the west. From the unit mph (miles per hour), we know its a magnitude of velocity. West indicates the direction. Hence, the given quantity is a vector -velocity.
It is not speed because speed only indicates the magnitude and not the direction. speed is a scalar quantity.
Answer: option A) initially increases, then decreases.
Justification:
The increase of the rate of effective collisions among particles as the temperature increases is explained by the collision theory in virtue of the increase of the kinetic energy.
This is, as the temperature increase so the kinetic energy increase and the higher the kinetic energy the greater the number of collisions and the greater the chances that this energy overcome the activation energy (the energy needed to start the reaction).
Now, as the reaction progress the number of reactants particles naturally decrease (some of them have been converted into product) so this lower number of particles means lower concentration which means lower collisions and, thereafter, a decrease in the reaction rate.
A unit of acceleration needs a unit of length in the numerator
and a squared unit of time in the denominator.
Example: meters / second²
feet / minute²
smoots / hour²
furlongs / fortnight² .
Ideally, in order to completely describe an acceleration vector,
you also need to state a direction.
Answer:
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Explanation:
Potential energy is when a object is not in motion and the ball is sitting on a shelf not being thrown around or rolling. kinetic energy is when a obeject is in motion and moving.
The answer you have is right good job 12
