Answer:
Explanation:
There are several differences between a physical and chemical change in matter or substances. A physical change in a substance doesn't change what the substance is. In a chemical change where there is a chemical reaction, a new substance is formed and energy is either given off or absorbed.
Answer:
force for start moving is 7.49 N
force for moving constant velocity 2.25 N
Explanation:
given data
mass = 7.65 kg
kinetic coefficient of friction = 0.030
static coefficient of friction = 0.10
solution
we get here first weight of block of ice that is
weight of block of ice = mass × g
weight of block of ice = 7.65 × 9.8 = 74.97 N
so here Ff = Fa
so for force for start moving is
Fa = weight × static coefficient of friction
Fa = 74.97 × 0.10
Fa = 7.49 N
and
force for moving constant velocity is
Fa = weight × kinetic coefficient of friction
Fa = 74.97 × 0.030
Fa = 2.25 N
Answer:
E. 3h
Explanation:
We know that
u = 0 m/s.
velocity after t = 1s
v = u+gt = 0+9.81 x 1s= 9.81 m/s
distance covered in 1st sec
= =>> ut+0.5 x g x t²
=>>0 + 0.5x 9.81 x 1 = 4.90m
Let 4.90 be h
distance travelled in 2nd second will now be used
So velocity after t = 1s
=>>1 x t+ 0.5 x g x t²
=>9.81x 1 + 0.5 x 9.81 x 1 = 3 x 4.90
So since h= 4.90
Then the ans is 3x h = 3h
Answer:
831.4 J
Explanation:
Info given:
mass adult: 82.5kg
mass child: 14.7kg
height of wall: 1.25m
g = 9.81m/s^2
PE = mgh
For adult:
mgh = (82.5kg)(9.81m/s^2)(1.25m) = 1011.65 J
For child:
mgh = (14.7kg)(9.81m/s^2)(1.25m) = 180.25 J
Difference in PE: 1011.65 J - 180.25 J = 831.4 J
Answer:
d = 1.07 mile
Explanation:
The rationale for this method is that the speed of light is much greater than the speed of sound, the definition of speed in uniform motion is
v = d / t
d = v t
the speed of sound is worth
v = 343 m / s
Therefore, the speed of sound must be multiplied by time to do this, all the units must be in the same system, as the distance in miles is requested
v = 343 m/s (1mile/1609 m) (3600s/1 h) = 343 (2.24) = 767.4 mile/h
v = 343 m / s (1 mile / 1609 m) = 0.213, mile/ s
If the measured time is t = 5s we multiply it by the speed
we substitute
d = 0.213 5
d = 1.07 mile
If you want to calculate the speed, this method in general is not widely used, since you must know the distance where the lightning occurred, which is relatively complicated.
