Assume biological substances are 90 percent water and the density of water is 1.0 ✕ 103 kg/m3.

An object moving forward at 10 m/s suddenly begins moving backward at 5 m/s. What is the most accurate explanation for this chan

Vinil7 [7]

My best guess would be C.

8 0

2 years ago

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The data table below shows the distribution of the energies of a pendulum 0.60 s into its motion. What is the missing value?

ohaa [14]

The total energy (also called mechanical energy) is the sum of the kinetic energy and potential energy:
$TE = KE + PE$
For this pendulum, we see that at t=0.60 s the total energy is TE=0.918 J while the potential energy is 0.054 J, so the kinetic energy (the missing value in the table) is
$KE=TE-PE=0.918 J - 0.054 J =0.864 J$

4 0

2 years ago

Baseball player a bunts the ball by hitting it in such a way that it acquires an initial velocity of 2.4 m/s parallel to the gro

LUCKY_DIMON [66]

Let $\mathbf r_A$ denote the position vector of the ball hit by player A. Then this vector has components

$\begin{cases}r_{Ax}=\left(2.4\,\frac{\mathrm m}{\mathrm s}\right)t\\r_{Ay}=1.2\,\mathrm m-\frac12gt^2\end{cases}$

where $g=9.8\,\dfrac{\mathrm m}{\mathrm s^2}$ is the magnitude of the acceleration due to gravity. Use the vertical component $r_{Ay}$ to find the time at which ball A reaches the ground:

$1.2\,\mathrm m-\dfrac12\left(9.8\,\dfrac{\mathrm m}{\mathrm s^2}\right)t^2=0\implies t=0.49\,\mathrm s$

The horizontal position of the ball after 0.49 seconds is

$\left(2.4\,\dfrac{\mathrm m}{\mathrm s}\right)(0.49\,\mathrm s)=12\,\mathrm m$

So player B wants to apply a velocity such that the ball travels a distance of about 12 meters from where it is hit. The position vector $\mathbf r_B$ of the ball hit by player B has

$\begin{cases}r_{Bx}=v_0t\\r_{By}=1.6\,\mathrm m-\frac12gt^2\end{cases}$

Again, we solve for the time it takes the ball to reach the ground:

$1.6\,\mathrm m-\dfrac12\left(9.8\,\dfrac{\mathrm m}{\mathrm s^2}\right)t^2=0\implies t=0.57\,\mathrm s$

After this time, we expect a horizontal displacement of 12 meters, so that $v_0$ satisfies

$v_0(0.57\,\mathrm s)=12\,\mathrm m$

$\implies v_0=21\,\dfrac{\mathrm m}{\mathrm s}$

5 0

3 years ago

What physics principle is used in radar guns to find the speeds of tennis balls and baseballs at sporting events?

Luda [366]

<h2>Answer: Doppler effect </h2>

Explanation:

A radar gun (also known as a Doppler radar) uses the Doppler effect when measuring "return echoes" after having sent a microwave signal (a type of electromagnetic radiation).

In this context the Doppler effect consists of the change in a wave perceived frequency when the emitter of the waves, and the observer move relative to each other.

In the case of radars, a microwave signal is sent to a target (the tennis or baseball in this case) and then is reflected after "hitting" the target, so that the radar system measures this difference between the sent signal and the reflected signal.

6 0

3 years ago

Which of these would best describe the outcome of increasing the kinetic energy of the molecules in the above picture? A) The te

VikaD [51]

Answer: Option (A) is the correct answer.

Explanation:

Relation between kinetic energy and temperature is as follows.

$K.E \propto \frac{3}{2}kT$

As, kinetic energy is directly proportional to temperature. So, when there will be increase in temperature then there will also occur increase in kinetic energy of the particles of a substance.

And, when gas particles move slowly then it means kinetic energy of gas particles is very low. It also implies that temperature is low.

Thus, we can conclude that temperature will increase best describes the outcome of increasing the kinetic energy of the molecules in the above picture.

8 0

3 years ago

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