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3 years ago

Which of these examples has the most kinetic energy?

Physics

2 answers:

ch4aika [34]3 years ago

8 0

The answer would be A.a fully charged car battery

gavmur [86]3 years ago

3 0

The answer is C. A skydiver floating down on a parachute.

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Two asteroids collide and stick together. The first asteroid has mass of 1.50 × 104 kg andis initially moving at 0.77 × 103 m/s.

KengaRu [80]

Answer:

Magnitude 900m/s, direction 12.8° respect to the velocity of the first asteroid.

Explanation:

This is a perfectly inelastic collision, because the two asteroids stick together at the end. That means that the kinetic energy doesn't conserves, but the linear momentum does. But, since the velocities of the asteroids have different directions, we have to break down them in components. For convenience, we will take the direction of the first asteroid as x-axis, and its perpendicular direction (in the plane of the two velocity vectors) as y-axis. So, we have that:

$p_{1ox}+p_{2ox}=p_{fx}\\\\p_{2oy}=p_{fy}$

And, since $p=mv$ , we get:

$m_1v_{1o}+m_2v_{2o}\cos\theta=(m_1+m_2)v_{fx}\\\\m_2v_{2o}\sin\theta=(m_1+m_2)v_{fy}$

Solving for v_fx and v_fy, and calculating their values, we get:

$v_{fx}=\frac{m_1v_{1o}+m_2v_{2o}\cos\theta}{m_1+m_2}\\\\\implies v_{fx}=\frac{(1.50*10^{4}kg)(0.77*10^{3}m/s)+(2.00*10^{4}kg)(1.02*10^{3}m/s)\cos20\°}{1.50*10^{4}kg+2.00*10^{4}kg}=878m/s\\\\\\v_{fy}=\frac{m_2v_{2o}\sin\theta}{m_1+m_2}\\\\\implies v_{fy}=\frac{(2.00*10^{4}kg)(1.02*10^{3}m/s)\sin20\°}{1.50*10^{4}kg+2.00*10^{4}kg}=199m/s$

Now, the final speed can be calculated using the Pythagorean Theorem:

$v_f=\sqrt{v_{fx}^{2}+v_{fy}^{2}} \\\\\implies v_f=\sqrt{(878m/s)^{2}+(199m/s)^{2}}=900m/s$

And the direction $\beta=\arctan \frac{v_{fy}}{v_{fx}}\\ \\\implies \beta=\arctan\frac{199m/s}{878m/s}=12.8\°$ can be obtained using trigonometry:

$\beta=\arctan \frac{v_{fy}}{v_{fx}}\\ \\\implies \beta=\arctan\frac{199m/s}{878m/s}=12.8\°$

That means that the final velocity of the two asteroids has a magnitude of 900m/s and a direction of 12.8° with respect to the velocity of the first asteroid.

7 0

3 years ago

An object is dropped from a bridge. A second object is thrown downwards 1.0 s later. They both reach the water 20 m below at the

olga2289 [7]

Answer:

vi = 14.610

Explanation:

initial velocity of the first object (vi) = 0 m/s, because it was dropped

distance (y) = -20 m

initial position (y0) = 0 m

acceleration due to gravity (g) = -9.8 m/s^2

y = 1/2 gt^2 + vi*t + y0

-20 = 1/2(-9.8)t^2 + 0 + 0

-20 = -4.9t^2

4.081 = t^2

+√4.081 = t

t = 2.020

time of second object = 2.020 - 1 = 1.020

Now we can plug in the new time to solve for vi of the second object.

y = 1/2 gt^2 + vi*t + y0

-20 = 1/2(-9.8)1.020^2 + vi*1.020 + 0

-20 = -5.098 + 1.020vi

14.902 = 1.020vi

vi = 14.610 m/s

6 0

3 years ago

A 10-kg piece of aluminum sits at the bottom of a lake, right next to a 10-kg piece of lead, which is much denser than aluminum.

Lelechka [254]

I think that the answer is B

5 0

3 years ago

Read 2 more answers

What motivates the squire in lines 85- 90?

just olya [345]

<span>Answer: If you mean the Knight in the prologue, the man traveling with his son (the Squire) and a Yeoman, he is traveling to Canterbury to give thanks for his safe return from the wars in the Baltic. We're told that he has never been known to speak unkindly to anyone, a fact that sums up his chivalrous upbringing. Evidently he feels strongly motivated to live by a code of high standards and refined behavior.</span>

5 0

4 years ago

When turned on, a fan requires 5.0 seconds to get up to its final operating rotational speed of 1200 rpm. a) How large is the fi

vova2212 [387]

Answer:

125.6 rad/s

25.12 rad/s²

Explanation:

t = time required by the fan to get up to final operating speed = 5 sec

w = final operating rotational speed = 1200 rpm

we know that :

1 revolution = 2π rad

1 min = 60 sec

w = $1200\frac{rev}{min}\frac{2\pi rad}{1 rev}\frac{1 min}{60 sec}$

w = $\frac{1200\times 2\pi }{60}\frac{rad}{s}$

w = 125.6 rad/s

w₀ = initial angular speed = 0 rad/s

α = angular acceleration

using the equation

w = w₀ + α t

125.6 = 0 + α (5)

α = 25.12 rad/s²

5 0

3 years ago