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3 years ago

If a car travels 23.8 meters in 4.2 seconds, what is its speed?

1 answer:

5 0

Displacement = Initial Velocity * time + 0.5 * acceleration * time^2

Initial velocity * time = 0 since we assume that the car is launching from start without motion.

So, displacement = 0.5 * acceleration * time ^ 2

23.8 = 0.5 * acceleration * 4.2^2

23.8 = 0.5 * 17.64 * acceleration

23.8 = 8.82 * acceleration

23.8/8.82 = acceleration = 2.69 m/s^2

Final Velocity = initial velocity + acceleration * time

Final velocity = 0 + 2.69 * 4.2 = 11.3 m/s

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A distant large asteroid is detected that might pose a threat to Earth. If it were to continue moving in a straight line at cons

Vlada [557]

Answer:

The minimum speed required is 5.7395km/s.

Explanation:

To escape earth, the kinetic energy of the asteroid must be greater or equal to its gravitational potential energy:

$K.E\geq P.E$

$\dfrac{1}{2}mv^2 \geq G\dfrac{Mm}{R}$

where $m$ is the mass of the asteroid, $R= 24,000,000\:m$ is its distance form earth's center, $M = 5.9*10^{24}kg$ is the mass of the earth, and $G = 6.7*10^{-11}m^3/kg\: s^2$ is the gravitational constant.

Solving for $v$ we get:

$v \geq \sqrt{\dfrac{2GM}{R} }$

putting in numerical values gives

$v \geq \sqrt{\dfrac{2(6.7*10^{-11})(5.9*10^{24})}{(24,000,000)} }$

$\boxed{v\geq 5739.5m/s}$

in kilometers this is

$v\geq5.7395m/s.$

Hence, the minimum speed required is 5.7395km/s.

5 0

3 years ago

Definition: A potential path for the flow of electricity with at least one gap in the path that prevents this flow. The gap is u

Andreas93 [3]

Answer:

Open circuit

Explanation:

An open circuit is simply an electrical circuit that is not complete. In such a circuit, there is a gap and this will not allow the electric current to pass through.

Despite all the elements being complete in the circuit, an open circuit will halt the flow of electric current and will not do deliver the necessary energy it is supposed to.

In such a circuit, the wires are cut of and not connected properly.

The reverse is a closed circuit.

7 0

3 years ago

Read 2 more answers

An ideal gas in a piston is placed in a refrigerator, which removes 413 J of energy from the gas via cooling. The plunger on the

maria [59]

Answer:

The net change in the internal energy of the gas in the piston is -343J

Explanation:

Because heat and workdone are the only means of energy transfer between the system and the surrounding, change in internal energy is given by;

∆E = q + w

q = heat transfer

w = workdone

Because heat is lost by the system, the heat transfer is negative

q = -413J

Because work is done on the system, workdone is positive

w = +70J

∆E = -413J + 70J

∆E = -343J

5 0

3 years ago

Which of the following are results of the force of gravity?

docker41 [41]

Hello,

Here is your answer:

The proper answer for this question is option B "When released,a book falls to the ground". That's because of gravity the book will hit the ground!

Your answer is B.

If you need anymore help feel free to ask me!

Hope this helps.

7 0

4 years ago

Read 2 more answers

Question 2

Delvig [45]

Answer:

Approximately $73\; {\rm N}$ , assuming that the acceleration of this ball is constant during the descent.

Explanation:

Assume that the acceleration of this ball, $a$ , is constant during the entire descent.

Let $x$ denote the displacement of this ball and let $t$ denote the duration of the descent. The SUVAT equation $x = (1/2)\, a\, t^{2}$ would apply.

Rearrange this equation to find an expression for the acceleration, $a$ , of this ball:

$\begin{aligned} a &= \frac{2\, x}{t^{2}}\end{aligned}$ .

Note that $x = 11\; {\rm m}$ and $t = 1.5\; {\rm s}$ in this question. Thus:

$\begin{aligned} a &= \frac{2\, x}{t^{2}} \\ &= \frac{2 \times 11\; {\rm m}}{(1.5\; {\rm s})^{2}} \\ &\approx 9.78\; {\rm m \cdot s^{-2}}\end{aligned}$ .

Let $m$ denote the mass of this ball. By Newton's Second Law of Motion, if the acceleration of this ball is $a$ , the net external force on this ball would be $m\, a$ .

Since $m = 7.5\; {\rm kg}$ and $a \approx 9.78\; {\rm m\cdot s^{-2}}$ , the net external force on this ball would be:

$\begin{aligned} (\text{net force}) &= m\, a \\ &\approx 7.5\; {\rm kg} \times 9.78\; {\rm m\cdot s^{-2}} \\ &\approx 73\; {\rm kg \cdot m \cdot s^{-2} \\ &= 73\; {\rm N} && (1\; {\rm N} = 1\; {\rm kg \cdot m\cdot s^{-2}}) \end{aligned}$ .

4 0

2 years ago