Matter either loses or absorbs energy when it changes from one state to another. For example, when matter changes from a liquid to a solid, it loses energy. The opposite happens when matter changes from a solid to a liquid. For a solid to change to a liquid, matter must absorb energy from its surroundings.
Answer:
Force, F = 187.42 N
Explanation:
It is given that,
Mass of boy, m = 30 kg
Acceleration due to gravity, 
Radius of curvature of the roller coaster, r = 15 m
Speed of the car, v = 7.3 m/s
The force acting on the boy are force of gravity and the centripetal force. The net force acting on him is as follows :
F = 187.42 N
So, he press against the seat with a force is 187.42 N. Hence, this is the required solution.
Both cells are formed in bone marrow.....but t cells matures into thymus....and b cells matures into bone marrow ! both helps in defense !
B cells can connect to antigens right on the surface of the invading virus or bacteria.
T- cells can only connect to virus antigens on the outside of infected cells.
for more info , comment !
The water cycle is all about storing water and moving water on, in, and above the Earth. Although the atmosphere may not be a great storehouse of water, it is the superhighway used to move water around the globe. Evaporation and transpiration change liquid water into vapor, which ascends into the atmosphere due to rising air currents. Cooler temperatures aloft allow the vapor to condense into clouds and strong winds move the clouds around the world until the water falls as precipitation to replenish the earthbound parts of the water cycle. About 90 percent of water in the atmosphere is produced by evaporation from water bodies, while the other 10 percent comes from transpiration from plants.
There is always water in the atmosphere. Clouds are, of course, the most visible manifestation of atmospheric water, but even clear air contains water—water in particles that are too small to be seen. One estimate of the volume of water in the atmosphere at any one time is about 3,100 cubic miles (mi3) or 12,900 cubic kilometers (km3). That may sound like a lot, but it is only about 0.001 percent of the total Earth's water volume of about 332,500,000 mi3 (1,385,000,000 km3), If all of the water in the atmosphere rained down at once, it would only cover the globe to a depth of 2.5 centimeters, about 1 inch.
50 +50 =100 Since it’s sitting on a 50m cliff that’s high with a mass of 50 kg it would be adding because once it goes down it’s adding speed
