488 J of work is done to a box which is moved across the floor for a distance of 8.9 m. What net force is required to act on the
1 answer:
You might be interested in
A) 750 m
First of all, let's find the wavelength of the microwave. We have
is the frequency
is the speed of light
So the wavelength of the beam is
Now we can use the formula of the single-slit diffraction to find the radius of aperture of the beam:
where
m = 1 since we are interested only in the central fringe
D = 30 km = 30,000 m
a = 2.0 m is the aperture of the antenna (which corresponds to the width of the slit)
Substituting, we find
and so, the diameter is
B) 0.23 W/m^2
First we calculate the area of the surface of the microwave at a distance of 30 km. Since the diameter of the circle is 750 m, the radius is
So the area is
And since the power is
The average intensity is
Answer:
A) mass = 3121.58 kg
B) tension = 25940.37 N
C) tension = 25940.37 N (tension on both sides will be the same)
Explanation:
Weight of elevator = 22500 N
Distance = 6.75 m
Time = 3 sec
Since it started from rest, initial speed is zero.
Using Newton's equation of motion we have,
S = ut + 0.5at^2
S = distance covered = 6.75 m
t = time = 3 s
a = acceleration upwards
u = initial velocity = 0
Substituting values, we have,
6.75 = 0(3) + (0.5 x a x 3^2)
6.75 = 4.5a
a = 6.75/4.5 = 1.5 m/s^2 (acceleration of the elevator upwards)
Mass of the elevator = Weight/g
Where g = acceleration due to gravity 9.81 m/s
Mass = 22500/9.81 = 2293.58 kg
From the image below we solve from
T - 22500 = ma
T - 22500 = 2293.58 x 1.5
T - 22500 = 3440.37
T = 3440.37 + 22500 = 25940.37 N (this is the tension on the rope)
On the other side,
mg - T = ma
9.81m - 25940.37 = 1.5m
(9.81 - 1.5)m = 25940.37
8.31m = 25940.37
m = 3121.58 kg (mass of counter weight)
See image below
