We use the formula,
.
Here, v is velocity and its value given 26 mi/h ( in m/s, 
) and d is distance and its value is given 80 m.
Substituting these values in above formula we get,
Thus, the time delay between green lights on successive blocks to keep the traffic moving continuously is 6.88 s
We can solve the problem by requiring the equilibrium of the forces and the equilibrium of torques.
1) Equilibrium of forces:
where
is the weight of the person
is the weight of the scaffold
Re-arranging, we can write the equation as
(1)
2) Equilibrium of torques:
where 3 m and 2 m are the distances of the forces from the center of mass of the scaffold.
Using
and replacing T1 with (1), we find
from which we find
And then, substituting T2 into (1), we find
Refer to the diagram shown below.
Assume that
(a) The piano rolls down on frictionless wheels,
(b) Wind resistance is negligible.
The distance along the ramp is
d = (1.3 m)/sin(22°) = 3.4703 m
The component of the piano's weight along the ramp is
mg sin(22°)
If the acceleration down the ramp is a, then
ma = mg sin(22°)
a = g sin(22°) = (9.8 m/s²) sin(22°) = 3.671 m/s²
The time, t, to travel down the ramp from rest is given by
(3.4703 m) = 0.5*(3.671 m/s²)*(t s)²
t² = 3.4703/1.8355 = 1.8907
t = 1.375 s
Answer: 1.375 s
An element is composed of millions of atoms and a compound is composed of molecules. When an atom reacts with another atom, a molecule is formed.
For example, if sodium reacts with chloride, it forms sodium chloride (Common salt). Here, sodium and chloride are elements and sodium chloride is a molecule. In this way, millions of atoms of sodium reacts with chloride and forms common salt.
Again, when the common salt is mixed with other compounds such as water, it forms a mixture.
