True or False? All electromagnetic waves travel at the same speed through a vacuum.

On a cold day, a heat pump absorbs heat from the outside air at 14°F (−10°C) and transfers it into a home at a temperature of 86

Leto [7]

Answer:

6.575

Explanation:

T1 = 30C = 30 + 273 = 303 K

T2 = - 10 C = - 10 + 273 = 263 K

The coefficient of performance of heat pump

k = T2 / (T1 - T2)

k = 263 / (303 - 263) = 6.575

7 0

3 years ago

In which one of the following circumstances could mechanical energy not possibly be conserved, even if friction and air resistan

qwelly [4]

Answer:

A car moves up a hill at a constant velocity

Explanation:

Since the velocity is constant, the speed is also constant and so is the kinetic energy. However, total mechanical energy is sum of gravitational potential energy and kinetic energy, and the car is moving up the hill so its potential energy rises.

Thus, in the circumstances described the mechanical energy cannot be conserved.

The correct answer is A car moving up the hill with constant velocity.

5 0

3 years ago

as an aid in understanding this problem. The drawing shows a positively charged particle entering a 0.61-T magnetic field. The p

miv72 [106K]

Answer:

E = 420.9 N/C

Explanation:

According to the given condition:

$Net\ Force = 2(Magnetic\ Force)\\Electric\ Force - Magnetic\ Force = 2(Magnetic\ Force)\\Electric\ Force = 3(Magnetic\ Force)\\qE = 3qvBSin\theta\\E = 3vBSin\theta$

where,

E = Magnitude of Electric Field = ?

v = speed of charge = 230 m/s

B = Magnitude of Magnetic Field = 0.61 T

θ = Angle between speed and magnetic field = 90°

Therefore,

$E = (3)(230\ m/s)(0.61\ T)Sin90^o$

3 0

3 years ago

Choose the 200 kg refrigerator. set the applied force to 400 n (to the right). be sure friction is turned off. what is the net f

Firlakuza [10]

The net force acting on the refrigerator is 400 N to the right.

<h3></h3><h3>FURTHER EXPLANATION</h3>

The net force or resultant force is the sum of all the forces acting on a body or an object in x and y axes.

Forces along the y-axis The forces that usually act on an object vertically (in the y-axis) are: gravitational force which is a downward force and the normal force which is an upward (perpendicular) force exerted by a surface on an object resting above it that keeps the object from falling.
Forces along the x-axis These include the force or forces applied to cause a left or right motion of an object along the horizontal plane (called the Applied Force) and the force that opposes the motion or friction.

In this problem the forces acting on the x and y - axes can be determined:

Along the x-axis:

gravitational force = -1960 N
normal force = +1960 N
Net force = -1960 N + 1960 N = 0

The gravitational force is the weight of the object obtained by multiplying the mass of the object (in kg) with the acceleration due to gravity, 9.8 m/s^2. It is given a negative (-) sign to indicate that it is a downward force.

Since the object is not falling through the surface, it can be assumed that the gravitational force and normal force are balanced. Hence, the size of the normal force is the same as the gravitational force but with the opposite direction indicated by the + sign for an upward force.

The forces along the x-axis are balanced (i.e. net force is zero) so the object neither moves upward or downward.

Along the y-axis