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Irina-Kira [14]
3 years ago
13

The distance from Earth to the North Star is about 430 light-years. Which of the following statements describes why scientists u

se the light-year unit to measure distance in space?
A.) A light-year is very small and distance in space are very small

B.) A light-year unit is very small and the distance in space are very large

C.) A light-year unit is very large and distance in space are very small

D.) A light-year unit is very large and distance in space are very large
Physics
1 answer:
vampirchik [111]3 years ago
7 0

Answer:

D

Explanation:

D

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Which of the following is a push or pull?
Nutka1998 [239]

Answer: A. Newton

Explanation:

A force is a push or pull exerted on an object and a newton is the type of measurement for a force.

4 0
3 years ago
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A 81 kg man is riding on a 40 kg cart traveling at a speed of 2.3 m/s. He jumps off with zero horizontal speed relative to the g
Alexus [3.1K]

Answer:

\Delta v= 4.66\frac{m}{s}

Explanation:

In this case we have to use the Principle of conservation of Momentum:

<em>This principle says that in a system  the total momentum is constant if no external forces act in the system. The formula is:</em>

m_1v_1+m_2v_2=m_1u_1+m_2u_2

<em>Where:</em>

m_1: Mass of the first object.

m_2: Mass of the second object.

v_1: Initial velocity of the first object.

v_2: Initial velocity of the second object.

u_1: Final velocity of the first object.

u_2: Final velocity of the second object.

In <u>this problem</u> we have:

m_1=81kg\\m_2=40kg\\v_1_2=2.3\frac{m}{s}

u_1=0\frac{m}{s}

Observation: v_1_2: Is because the system has the same initial velocity.

First we have to find u_2,

m_1v_1+m_2v_2=m_1u_1+m_2u_2

We can rewrite it as:

(m_1+m_2)v_1_2=m_1u_1+m_2u_2

Replacing with the data:

(m_1+m_2)v_1_2=m_1u_1+m_2u_2\\\\(81kg+40kg)2.3\frac{m}{s}=81kg(0\frac{m}{s})+40kg(u_2)\\\\(121kg)2.3\frac{m}{s}=40kg(u_2)\\\\\frac{(121kg)2.3\frac{m}{s}}{40kg}=u_2\\\\\frac{278.3}{40}\frac{m}{s}=u_2\\\\6.96\frac{m}{s}=u_2

We found the final velocity of the cart, but the problem asks for the resulting change in the cart speed, this means:

\Delta v=u_2-v_2\\\Delta v=6.96\frac{m}{s}-2.3\frac{m}{s}\\\Delta v= 4.66\frac{m}{s}

Then, the resulting change in the cart speed is:

\Delta v= 4.66\frac{m}{s}

5 0
3 years ago
A horizontal spring with spring constant 750 N/m is attached to a wall. An athlete presses against the free end of the spring, c
ANTONII [103]

Answer:

37.5 N Hard

Explanation:

Hook's law: The force applied to an elastic material is directly proportional to the extension provided the elastic limit of the material is not exceeded.

Using the expression for hook's law,

F = ke.............. Equation 1

F = Force of the athlete, k = force constant of the spring, e = extension/compression of the spring.

Given: k = 750 N/m, e = 5.0 cm = 0.05 m

Substitute into equation 1

F = 750(0.05)

F = 37.5 N

Hence the athlete is pushing 37.5 N hard

4 0
3 years ago
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An airplane traveling from San Francisco northeast to Chicago travels 1260 km in 3.5 h. What is the airplanes average velocity?
IrinaK [193]

Answer:

Average velocity = 360km/h due Northeast.

Explanation:

Given the following data;

Distance = 1260km

Time = 3.5h.

Velocity =?

Velocity can be defined as the rate of change in displacement (distance) with time. Velocity is a vector quantity and as such it has both magnitude and direction.

Mathematically, velocity is given by the equation;

Velocity = \frac{distance}{time}

V = \frac{d}{t}

Substituting into the above equation;

V = \frac{1260}{3.5}

Velocity, V = 360km/h.

Since velocity is a vector quantity, it must have both magnitude and direction.

<em>Hence, the average velocity of the airplane is 360km/h due Northeast. </em>

6 0
4 years ago
I NEED THIS DONE ASAP I WILL MARK YOU THE BRAINLIEST BUT NO LINKS
Cloud [144]

Answer:

1. Static Friction

2. Sliding friction

3. Fluid friction

4. is rolling friction

Sorry if i am wrong

Explanation:

4 0
3 years ago
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