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2 years ago

Which of the following describes a chemical change?

Physics

1 answer:

Thepotemich [5.8K]2 years ago

4 0

Answer:

D. Burning paper

Explanation:

physical change is just changing the way it looks

chemical change is changing the properties of the object or thing

melting ice is just changing the way it looks it still has the same atoms and elements.

when you burn something it will change the properties of the atoms in the object

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An astronaut exploring a distant solar system lands on an unnamed planet with a radius of 2530 km. When the astronaut jumps upwa

Natali [406]

Answer:

1.38*10^18 kg

Explanation:

According to the Newton's law of universal gravitation:

$F=G*\frac{m_a*m_p}{r^2}$

where:

G= Gravitational constant (6.674×10−11 N · (m/kg)2)

ma= mass of the astronaut

mp= mass of the planet

$F=m_a.a\\(v_f )^2=(v_o)^2+2.a.\Delta y\\\\a=\frac{(v_f)^2-(v_o)^2}{2.\Delta y}\\\\a=\frac{(0)^2-(4.29m/s)^2}{2.0.64m}=14.38m/s^2\\\\F=m_a*14.38m/s^2$

so:

$m_a*14.38m/s^2=(6.674*10^{-11}N.(m/kg)^2)*\frac{m_a.m_p}{(2.530*10^3m)^2}\\m_p=\frac{14.38m/s^2(2.530*10^3m)^2}{(6.674*10^{-11}N.(m/kg)^2)}\\\\m_p=1.38*10^{18}kg$

7 0

3 years ago

In his explanation of the threshold frequency in the photoelectric field, Einstein reasoned that the absorbed photon must have t

Doss [256]

Answer:

4.6×10^-7 m or 0.46nm

Explanation:

From

Wo= hc/λ

Where:

Wo= work function of the metal

h= planks constant

c= speed of light

λ= wavelength

λ= hc/Wo

λ= 6.6×10^-34 × 3×10^8/4.30×10^-19

λ= 4.6×10^-7 m

5 0

2 years ago

Study the scenario.

Otrada [13]

If no other forces act on the object, according to Newton’s first law, the spacecraft will continue moving at a constant velocity, assuming that a planet or something with large mass doesn’t cross its path. Forces are not required to continue the motion of an object on a frictionless plane at a constant rate.

7 0

3 years ago

Read 2 more answers

SP 15The magnetic field in a region of space is measured to be:This field is known to be caused by a cluster of long-straight wi

tino4ka555 [31]

Answer:

i = 0.477 10⁴ B

the current flows in the counterclockwise

Explanation:

For this exercise let's use the Ampere law

∫ B . ds = μ₀ I

Where the path is closed

Let's start by locating the current vines that are parallel to the z-axis, so it must be exterminated along the x-axis and as the specific direction is not indicated, suppose it extends along the y-axis.

From BiotSavart's law, the field must be perpendicular to the direction of the current, so the magnetic field must go in the x direction.

We apply the law of Ampere the segment parallel to the x-axis is the one that contributes to the integral, since the other two have an angle of 90º with the magnetic field

Segment on the y axis

L₀ = (y2-y1)

L₀ = 3-0 = 3 cm

Segment on the point x = 2 cm

L₁ = 3-0

L₁ = 3cm

B L = μ₀ I

B 2L = μ₀ I

i = 2 L B /μ₀

i= 2 0.03 / 4π 10⁻⁷ B

i = 4.77 10⁴ B

The current is perpendicular to the magnetic field whereby the current flows in the counterclockwise

8 0

2 years ago

If a moving car speeds up until it is going twice as fast, how much kinetic energy doe s it have compared with its initial kinet

dezoksy [38]

The kinetic energy of an object of mass m and velocity v is given by
$K= \frac{1}{2} mv^2$

Let's call $v_i$ the initial speed of the car, so that its initial kinetic energy is
$K_i = \frac{1}{2} mv_i^2$
where m is the mass of the car.

The problem says that the car speeds up until its velocity is twice the original one, so
$v_f = 2 v_i$
and by using the new velocity we can calculate the final kinetic energy of the car
$K_f = \frac{1}{2} mv_f^2 = \frac{1}{2}m (2 v_i)^2 = 4 ( \frac{1}{2} mv_i^2)=4 K_i$
so, if the velocity of the car is doubled, the new kinetic energy is 4 times the initial kinetic energy.

6 0

2 years ago