3.24
<h2>Explanation:</h2><h2></h2>
Using Newton's law of motion,
F = ma ..........................(i)
where;
F = net force acting on the object (or body)
m = mass of the object (or body)
a = acceleration of the body.
<em>In this case,</em>
Two forces are acting;
(i)The weight (W) of the man = m x g = 62 x 10 = 620N
(ii)The tension (T) on the scale of the elevator = 821N
The weight(W) of the man is a downward force while the tension (T) on the scale of the elevator is an upward force. Since the elevator rises upward is positive.
Therefore,
Net force (F) = Total upward force(s) - Total downward force(s)
Net force (F) = 821 - 620
F = 201N
To calculate the acceleration of the elevator,
substitute the values of F = 201N and m = 62 into equation (i) above;
=> F = ma
=> 201 = 62 x a
=> a = 210 / 62
=> a = 3.24
Therefore the acceleration of the elevator is 3.24
Explanation:
It is given that,
Mass of object, m = 2 kg
Initial velocity, u = 3 m/s (east)
Final velocity, v = - 7 m/s (west)
The Impulse can be calculated using the change in momentum of an object i.e.
J = m(v-u)
J = -20 kg-m/s
So, the Impulse of this object is 20 kg-m/s but the direction is opposite. Hence, statement (1) is correct i.e. Student #1: "The impulse is equal to the change in momentum, which is (2 kg)(3 m/s + 7 m/s) = 20 kg m/s."
Answer:
A.
B.
C.
Explanation:
The capacitance of a capacitor is its ability to store charges. For parallel-plate capacitors, this ability depends the material between the plates, the common plate area and the plate separation. The relationship is
is the capacitance,
is the common plate area,
is the plate separation and
is the permittivity of the material between the plates.
For air or free space, is
called the permittivity of free space. In general,
where
is the relative permittivity or dielectric constant of the material between the plates. It is a factor that determines the strength of the material compared to air. In fact, for air or vacuum,
.
The energy stored in a capacitor is the average of the product of its charge and voltage.
Its charge, , is related to its capacitance by
(this is the electrical definition of capacitance, a ratio of the charge to its voltage; the previous formula is the geometric definition). Substituting this in the formula for
,
A. Substituting for in
,
B. When the distance is ,
C. When the distance is restored but with a dielectric material of dielectric constant, , inserted, we have