Explanation:
At night, when that part of Earth is facing away from the sun, space looks black because there 8s no nearby bright source of light like the sun , to be scattered
For this case you must first know the definition of density. D = m / v where, m: mass v: volume. You can then write the following hypothesis: IF you know two physical characteristics of an object then you can determine the density. First weigh the object, THEN measure its volume BECAUSE the density is the quotient between the mass and the volume of an object.
<span>Density is a value for
mass, such as kg, divided by a value for volume, such as m^3. Density is a
physical property of a substance that represents the mass of that substance per
unit volume. The mass of the salty water is calculated as follows:
Mass = 1.166 g/mL ( 2000 mL ) = 2332 g of salty water</span>
Answer:
so initial speed of the rock is 30.32 m/s
correct answer is b. 30.3 m/s
Explanation:
given data
h = 15.0m
v = 25m/s
weight of the rock m = 3.00N
solution
we use here work-energy theorem that is express as here
work = change in the kinetic energy ..............................1
so it can be written as
work = force × distance ...................2
and
KE is express as
K.E = 0.5 × m × v²
and it can be written as
F × d = 0.5 × m × (vf)² - (vi)² ......................3
here
m is mass and vi and vf is initial and final velocity
F = mg = m (-9.8) , d = 15 m and v{f} = 25 m/s
so put value in equation 3 we get
m (-9.8) × 15 = 0.5 × m × (25)² - (vi)²
solve it we get
(vi)² = 919
vi = 30.32 m/s
so initial speed of the rock is 30.32 m/s