If I was a scientist and I wanted to measure the intensity of an earthquake I would use

Alla [95]

Answer:

$1) \: \: \: 4Al+ 3MnO _{2}→ 3Mn + 2Al _{2} O _{3} \\ 2) \: \: \:2Ga + 3H _{2}SO _{4} → Ga _{2} (SO _{4}) _{3} +3 H _{2} \\ 3) \: \: \: Mg + 2HCI→ MgCl _{2}+ H _{2}$

4 0

3 years ago

Lenz’s law states that an induced magnetic field in a conductor true or false

Hunter-Best [27]

Let's say there's a magnetic field B passing through a conductor loop with an area A. The magnetic flux through the loop, if B is constant and perpendicular to the loop, is B multiplied by A. Now let's say the magnetic flux is changing. This can be caused by a combination of the strength of B changing, A changing, or the orientation of B or the loop changing.

Lenz's law states that the changing magnetic flux induces a current in the loop such that the induced current creates its own magnetic field to oppose the change in the flux.

5 0

4 years ago

At an accident scene on a level road, investigators measure a car's skid mark to be 98 m long. It was a rainy day and the coeffi

shutvik [7]

Answer:

The speed of the car was 28 m/s.

Explanation:

Hi there!

The initial kinetic energy of the car, KE, is equal to the negative work, W, done by friction to bring the car to stop. Let´s write the work-energy theorem:

W = ΔKE = final kinetic energy - initial kinetic energy

In this case, the final kinetic energy is zero, then:

W = - initial kinetic energy

Since the work done by friction is negative (the work is done in opposite direction to the movement of the car), then:

Wfr = initial kinetic energy

The work done by friction is calculated as follows:

Wfr = Fr · d

Where:

Fr = friction force.

d = distance.

The friction force is calculated as follows:

Fr = N · μ

Where:

N = normal force.

μ = coefficient of friction

Since the only vertical forces acting on the car are the weight of the car and the normal force, and the car is not being accelerated in the vertical direction, the normal force has to be equal to the weight of the car (with opposite sign).

Then the friction force can be written as follows:

Fr = m · g · μ

Where:

m = mass of the car.

g = acceleration due to gravity (9.8 m/s²)

The work done by friction will be:

W = m · g · μ · d

The equation of kinetic energy is the following:

KE = 1/2 · m · v²

Where

m = mass of the car.

v = speed.

Then:

W = KE

m · g · μ · d = 1/2 · m · v²

2 · g · μ · d = v²

2 · 9.8 m/s² · 0.40 · 98 m = v²

v = 28 m/s

The speed of the car was 28 m/s.

7 0

4 years ago

The tires of a car support the weight of a stationary car. If one tire has a slow leak, the air pressure within the tire will __

mrs_skeptik [129]

Answer:

The answer is E. Decrease, increase, decrease

Explanation:

The pressure within the tire wall is a result of the molecules of air colliding with the walls of the tire, if there is a leakage that means some or all of the air molecules will escape resulting in a decrease in the collision between the molecules and the tire wall which means the pressure decreases within the walls which also translates to a decrease in pressure exerted by the tire on the ground surface.

Before the leakage, the tire walls are kept tensed due to the internal pressure exerted by the air molecules. When the leakage occurs the air molecules escape and this makes the tire loose its firm upright shape thereby falling to the floor and creating an increase in the area of contact between the tire and the floor surface.

The force exerted on the floor by the tire is proportional to the the pressure exerted and the surface area through which this force is applied, though the pressure is seen to decrease and the surface area seen to increase, one must consider the weight loss due to the air molecules that escapes which causes the force to decrease.

8 0

3 years ago

Calculate the resulting speed of an airplane with an airspeed of 120 km/h pointing due north when it encounters a wind of 90 km/

STatiana [176]

Answer:

The resulting speed of the airplane is 150 Km/h

Explanation:

The airspeed of the plane is 120 Km/h due North. The wind came from West pointing to the East at 90 Km/h

Both speeds are acting in different directions, so they must be added as vectors. Both vectors and the resulting velocity (Vr) are shown in the image below

The magnitude of that velocity can be computed by using Pythagoras's theorem:

$Vr^2=120^2+90^2$

$Vr^2=14400+8100=22500$

$Vr=\sqrt{22500}=150$

The resulting speed of the airplane is 150 Km/h

8 0

3 years ago