Well, actually a heat engine using the Carnot cycle whose cold reservoir is maintained at 0 K could in principle be 100% efficient, even if the hot reservoir was merely at the ambient temperature. Since it costs no energy at all to maintain a heat reservoir at the ambient temperature as long as you have a perfect thermal connection to a large thermal capacitor like your swimming pool or a nearby aquifer you’d have built a perpetual motion machine.
Answer:
(A) 14.7 N
(B) 0.15 m
(C) the speed will become 24.8 m/s while wavelength becomes 0.21 m
Explanation:
frequency (f) = 120 Hz
mass (m) = 1.5 kg
linear mass density (μ) = 0.0480 kg/m
acceleration due to gravity (g) = 9.8 m/s^{2}
(A) tension on the rope (T) = mg = 1.5 x 9.8 = 14.7 N
speed =
speed =
speed = 17.5 m/s
(B) wavelength = velocity / frequency
wavelength = 17.5 / 120 = 0.15 m
(C) when the mass are increased to 3.00 kg
tension now becomes = mg = 3 x 9.8 = 29.4 N
therefore speed = = = 24.8 m/s
wavelength now becomes = velocity / frequency = 24.8 / 120 = 0.21 m
hence the speed will become 24.8 m/s while wavelength becomes 0.21 m
Answer:
The ball traveled 0.827 m
Explanation:
Given;
distance between the metal plates of the room, d = 3.1 m
mass of the glass, m = 1.1g
charge on the glass, q = 4.7 nC
speed of the glass ball, v = 4.8 m/s
voltage of the ceiling, V = +3.0 x 10⁶ V
The repulsive force experienced by the ball when shot to the ceiling with positive voltage, can be calculated using Coulomb's law;
F = qV/d
|F| = (4.7 x 10⁻⁹ x 3 x 10⁶) / (3.1)
|F| = 4.548 x 10⁻³ N
F = - 4.548 x 10⁻³ N
The net horizontal force experienced by this ball is;
The work done between the ends of the plate is equal to product of the magnitude of net force on the ball and the distance traveled by the ball.
W = K.E
Therefore, the ball traveled 0.827 m
Answer:
Friction acts in the opposite direction to the motion of the truck and box.
Explanation:
Let's first review the problem.
A moving truck applies the brakes, and a box on it does not slip.
Now when the truck is applying brakes, only it itself is being slowed down. Since the box is slowing down with the truck, we can conclude that it is friction that slows it down.
The box in the question tries to maintains its velocity forward when the brakes are applied. We can think of this as the box exerting a positive force relative to the truck when the brakes are applied. When we imagine this, we can also figure out where the static friction will act to stop this positive force. Friction will act in the negative direction. Or in other words, friction will act in the opposite direction to the motion of the truck and box. This explains why the box slows down with the truck, as friction acts to stop its motion.
Answer:
A: The acceleration is 7.7 m/s up the inclined plane.
B: It will take the block 0.36 seconds to move 0.5 meters up along the inclined plane
Explanation:
Let us work with variables and set
As shown in the attached free body diagram, we choose our coordinates such that the x-axis is parallel to the inclined plane and the y-axis is perpendicular. We do this because it greatly simplifies our calculations.
Part A:
From the free body diagram we see that the total force along the x-axis is:
Now the force of friction is where is the normal force and from the diagram it is
Thus
Therefore,
Substituting the value for we get:
Now acceleration is simply
The negative sign indicates that the acceleration is directed up the incline.
Part B:
Which can be rearranged to solve for t:
Substitute the value of and and we get:
which is our answer.
Notice that in using the formula to calculate time we used the positive value of , because for this formula absolute value is needed.