Answer:
Time = t = 6.62 s
Explanation:
Given data:
Height = h = 215 m
Initial velocity = 
= 0 m/s
gravitational acceleration = g = 9.8 m/s²
Time = t = ?
According to second equation of motion
As initial velocity is zero, So the first term of right hand side of above equation equal to zero.
t² = 
t =
t = 
t = 6.62 s
Answer:
No temperature change occurs from heat transfer if ice melts and becomes liquid water (i.e., during a phase change). For example, consider water dripping from icicles melting on a roof warmed by the Sun. Conversely, water freezes in an ice tray cooled by lower-temperature surroundings.
Explanation:
Energy is required to melt a solid because the cohesive bonds between the molecules in the solid must be broken apart such that, in the liquid, the molecules can move around at comparable kinetic energies; thus, there is no rise in temperature. Similarly, energy is needed to vaporize a liquid, because molecules in a liquid interact with each other via attractive forces. There is no temperature change until a phase change is complete. The temperature of a cup of soda initially at 0ºC stays at 0ºC until all the ice has melted. Conversely, energy is released during freezing and condensation, usually in the form of thermal energy. Work is done by cohesive forces when molecules are brought together. The corresponding energy must be given off (dissipated) to allow them to stay together Figure 2.
The energy involved in a phase change depends on two major factors: the number and strength of bonds or force pairs. The number of bonds is proportional to the number of molecules and thus to the mass of the sample. The strength of forces depends on the type of molecules. The heat Q required to change the phase of a sample of mass m is given by
Q = mLf (melting/freezing,
Q = mLv (vaporization/condensation),
where the latent heat of fusion, Lf, and latent heat of vaporization, Lv, are material constants that are determined experimentally.
Answer: 14. 49 m
Explanation:
We can solve this problem with the following equations:
(1)
(2)
Where:
is the horizontal distance between the cannon and the ball
is the cannonball initial velocity
since the cannonball was shoot horizontally
is the time
is the final height of the cannonball
is the initial height of the cannonball
is the acceleration due gravity
Isolating from (2):
(3)
(4)
(5)
Substituting (5) in (1):
(6)
Finally:
Answer:
10.23m/s^2
Explanation:
GIven data
mass of elevator = 2125 kg
Force= 21,750 N
Required
The maximum acceleration upward
F= ma
a= F/m
a=21,750/2125
a= 10.23m/s^2
Hence the acceleration is 10.23m/s^2
