200 kW of solar radiation is shining on a 300 m^2 parking lot. What is the insulation on the parking lot?
1 answer:
You might be interested in
Answer:
a) 6 times farther. b) 6 times longer.
Explanation:
Once released, in the horizontal direction, no other forces act on the ball, so it continues moving at the same initial velocity, which is given by the projection of the velocity vector in the horizontal direction, as follows:
vₓ = v* cos (25º) = 23 m/s * 0.906 = 20.8 m/s
In the vertical direction, the initial velocity is the projection of the velocity vector along the vertical axis, as follows:
vy = v* sin (25º) = 23 m/s * 0.422 = 9.72 m/s
Assuming that the acceleration is constant, and equal to 1/6*g, we can calculate the total time of flight, with the following kinematic equation for the vertical displacement:
If the total displacement in the vertical direction is 0 (which means that the time if the total time of flight), we can solve for t, as follows:
On earth, this time could be calculated in the same way:
As the time is defined by the vertical movement, we can find the horizontal distance travelled on the moon, as follows:
Δx = v₀ₓ * t = 20.8 m/s * 11. 9 s = 248.1 m
On earth, the distance travelled had been as follows:
Δx = v₀ₓ * t = 20.8 m/s * 1.98 s = 41.3 m
⇒ Δx(moon) / Δx(earth) = 248.1 / 41.3 = 6.00
b) As we have just found, the time of flight on the moon and on the earth are as follows:
tmoon = 11. 9 s
tearth = 1.98 s
⇒ t(moon) / t(earth) = 11.9 / 1.98 = 6.0
A) 19.6 m/s (downward)
B) 576 J
C) 19.6 m
D) Velocity: not affected, kinetic energy: doubles, distance: not affected
Explanation:
A)
An object in free fall is acted upon one force only, which is the force of gravity.
Therefore, the motion of an object in free fall is a uniformly accelerated motion (constant acceleration). Therefore, we can find its velocity by applying the following suvat equation:
where:
v is the velocity at time t
u is the initial velocity
is the acceleration due to gravity
For the object in this problem, taking downward as positive direction, we have:
(the object starts from rest)
Therefore, the velocity after
t = 2 s
is:
(downward)
B)
The kinetic energy of an object is the energy possessed by the object due to its motion.
It can be calculated using the equation:
where
m is the mass of the object
v is the speed of the object
For the object in the problem, at t = 2 s, we have:
m = 3 kg (mass of the object)
v = 19.6 m/s (speed of the object)
Therefore, its kinetic energy is:
C)
In order to find how far the object has fallen, we can use another suvat equation for uniformly accelerated motion:
where
s is the distance covered
u is the initial velocity
t is the time
a is the acceleration
For the object in free fall in this problem, we have:
u = 0 (it starts from rest)
(acceleration of gravity)
t = 2 s (time)
Therefore, the distance covered is
D)
Here the mass of the object has been doubled, so now it is
M = 6 kg
For part A) (final velocity of the object), we notice that the equation that we use to find the velocity does not depend at all on the mass of the object. This means that the value of the final velocity is not affected.
For part B) (kinetic energy), we notice that the kinetic energy depends on the mass, so in this case this value has changed.
The new kinetic energy is
where
M = 6 kg is the new mass
v = 19.6 m/s is the speed
Substituting,
And we see that this value is twice the value calculated in part A: so, the kinetic energy has doubled.
Finally, for part c) (distance covered), we see that its equation does not depend on the mass, therefore this value is not affected.