What happens to compass needles when a copper rod is placed at a 90 degree angle in the midst of them and electric current is flowing through the rod?
here, i hope this .
correct answers are 1.an increase or decrease in pressure 2.an increase or decrease in energy
all existing matter can undergo phase change it means they may transform from one state to another. phase change of a matter may occur due to change in energy and change in pressures.
for example there is an ice cube which is a solid and if we want to change it phase into liquid water for that purpose we have to supply some energy to ice cube it means we have to give some heat to ice cube. after supplying heat energy to the ice it will turn into water it means there is phase change from solid to liquid due to supplying the heat. similarly we can change the liquid water into solid ice cube by taking heat energy(reducing temperature) from the liquid water .
in some cases the matter doesn't want to undergo phase transformation. for example, oxygen will solidify at -361.8 degrees fahrenheit at standard pressure.but , it can change to solid state at warmer temperatures when the pressure is increased.
consider the upward direction of motion as positive and downward direction of motion as negative.
a = acceleration due to gravity in downward direction = - 9.8
v₀ = initial velocity of rock in upward direction = ?
v = final velocity of rock at the highest point = 0
t = time to reach the maximum height = 4.2 sec
using the kinematics equation
v = v₀ + a t
inserting the values
0 = v₀ + (- 9.8) (4.2)
v₀ = 41.2