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ICE Princess25 [194]
3 years ago
8

The auto in the sketch moves forward as the brakes are applied. A bystander says that during the interval of braking, the auto's

velocity and acceleration are in opposite directions. Do you agree or disagree?
Physics
1 answer:
Ivan3 years ago
3 0

Answer:

The statement is true: velocity and acceleration have opposite directions in the interval of braking.

Explanation:

Let's say we have a velocity v>0.

The acceleration a is the rate of change of the velocity v. This means that if v is <em>increasing during</em> time, then a must be positive. But if v is <em>decreasing over</em> time, then a will be negative (even though the velocity is positive).

Mathematically:

a=\frac{dv}{dt}

v decreases ⇒\frac{dv}{dt}

⇒a.

Example:

v(t)=e^{-t}>0 \\\\\frac{dv}{dt}=-te^{-t}

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Keith_Richards [23]

Answer:ugly nlikeieieisj

Explanation:ebebbebebebes

8 0
2 years ago
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A boat is traveling upstream in the positive direction of the x axis at 10 km/h with respect to the water of a river. The water
sasho [114]

Answer:

The velocity of the boat with respect to the ground is 3 km/h

Explanation:

The speed of an object is different depending on the reference system you use. This is called relative speed.

A boat travels upstream, this means that it moves in the opposite direction to the river current.

A boat travels upstream, this means that it moves in the opposite direction to the river current. Then, if the boat moves in the positive direction of the x axis at 10 km / h with respect to the water of a river, the water flows in the negative direction of the x axis at 7 km / h with respect to the ground.

This causes the speed of the boat relative to the ground to be calculated as follows:  

<em>VbG = Vbw - VwG </em>

where VbG is the speed of the boat relative to the ground, Vbw is the speed of the boat relative to the water of the river and VwG is the speed of the water relative to the ground.

So: VbG=10 km/h – 7 km/h

<u><em>VbG= 3 km/h </em></u>

The direction of this velocity is in the positive x-direction.

4 0
3 years ago
Three charges lie along the x axis. The positive charge q1 = 15 μC is at x= 2.0 m and the positive charge q2 = 6.0μC is at the o
Delicious77 [7]

Answer:

x = 0.775m

Explanation:

Conceptual analysis

In the attached figure we see the locations of the charges. We place the charge q₃ at a distance x from the origin. The forces F₂₃ and F₁₃ are attractive forces because the charges have an opposite sign, and these forces must be equal so that the net force on the charge q₃ is zero.

We apply Coulomb's law to calculate the electrical forces on q₃:

F_{23} = \frac{k*q_{2}*q_{3}}{x^2} (Electric force of q₂ over q₃)

F_{13} = \frac{k*q_{1}*q_{3}}{(2-x)^2} (Electric force of q₁ over q₃)

Known data

q₁ = 15 μC = 15*10⁻⁶ C

q₂ = 6 μC = 6*10⁻⁶ C

Problem development

F₂₃ = F₁₃

\frac{k*q_{2}*q_{3}}{x^2} = \frac{k*q_{1}*q_{3}}{(2-x)^2} (We cancel k and q₃)

\frac{q_2}{x^2}=\frac{q_1}{(2-x)^2}

q₂(2-x)² = q₁x²

6×10⁻⁶(2-x)² = 15×10⁻⁶(x)² (We cancel 10⁻⁶)

6(2-x)² = 15(x)²

6(4-4x+x²) = 15x²

24 - 24x + 6x² = 15x²

9x² + 24x - 24 = 0

The solution of the quadratic equation is:

x₁ = 0.775m

x₂ = -3.44m

x₁ meets the conditions for the forces to cancel in q₃

x₂ does not meet the conditions because the forces would remain in the same direction and would not cancel

The negative charge q₃ must be placed on x = 0.775 so that the net force is equal to zero.

6 0
3 years ago
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Identify the element that has nine protons
loris [4]
Fluorine has nine protons
5 0
3 years ago
Could I please get some help on this question I don’t understand .
Oksana_A [137]

Answer:

12.5 m/s

Explanation:

From the question given above, the following data were obtained:

Initial velocity (u) = 0 m/s

Height (h) = 8 m

Final velocity (v) at 8 m above the lowest point =?

NOTE: Acceleration due to gravity (g) = 9.8 m/s²

The velocity of the roller coaster at 8 m above the lowest point can be obtained as follow:

v² = u² + 2gh

v² = 0² + (2 × 9.8 × 8)

v² = 0 + 156.8

v² = 156.8

Take the square root of both side

v = √156.8

v = 12.5 m/s

Therefore, the velocity of the roller coaster at 8 m above the lowest point is 12.5 m/s.

5 0
3 years ago
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