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.
Yes because there is more temperature to cover in terms of hot water turning into cold and then solid water, and therefore hot water cools down faster, whereas cold water will take more time to become solid.
Explanation:
Energy can be converted from one form to another. Examples: Gasoline (chemical) is put into our cars, and with the help of electrical energy from a battery, provides mechanical (kinetic) energy. ... Similarly, purchased electricity goes into an electric bulb and is converted to visible light and heat energy.
Answer:
1. The nucleus is about 1/2 the size of the atom
Explanation:
Alpha particles are positive charge particles and they are bounced back by the nucleus because nucleus is also same size
Now in present experiment Rutherford found that very few alpha particles are bounced back along same path which shows that very small region inside the nucleus is having positive charge and rest part of the atom is empty.
Now if we found that half of the alpha particles are bounced back then it shows that size of the nucleus is very large now as compare to previous one because only nucleus can bounce back the alpha particles
so correct answer will be
1. The nucleus is about 1/2 the size of the atom
