Which definition most accurately describes the term emergent literacy ?

You have been hiking and come back to the camp with really cold hands.you put your hands over the wonderful fire your father has

bekas [8.4K]

The answer would be radiation because heat waves are being transferred

5 0

3 years ago

A ball of mass 0.7 kg flies through the air at low speed, so that air resistance is negligible. (a) What is the net force acting

Fed [463]

Answer:

A) Gravitational Force, $F=-6.86N$ .

B) The y component of momentum.

C) The x component of momentum will remain the same.

D)The y component of momentum decreases.

E)The z component of momentum will remain constant.

Explanation:

First, let the x-axis be positive in the same direction as the horizontal speed of the ball, let the y-axis be positive in the opposite direction of gravity.

A) since there is no air resistance, the only force acting on the ball is the gravitational force. This force is downwards so it is negative. The net force is

$F=-9.8*0.7=-6.86N$ .

B)Because the net force (and the only one) is on the y-axis, only the vertical component of the momentum will be changed due to the force.

C)Since there is no resistance of air, the ball behaves as in projectile motion problems, this means that the x component of the velocity remains constant, also does the mass. Remembering that momentum is velocity times mass, it can be easily seen that x component of momentum remains constant too.

D)The y component of momentum decreases, this is because gravity decreases the y component of the velocity.

E)Since there is no z component of the force there is no change in the z component of the momentum.

5 0

3 years ago

Calculate the density of the baseball. Use the formula D = m/V where D is the density, m is the mass, and V is the volume. Deter

garik1379 [7]

Answer: 0.73 g/cm3 and YES the questionable ball in this range of acceptable density

Explanation:

4 0

3 years ago

Read 2 more answers

Power Rating of a Resistor. The power rating of a resistor is the maximum power the resistor can safely dissipate without too gr

IgorLugansk [536]

(a) 273.9 V

The power rating of the resistor is given by

$P=\frac{V^2}{R}$

where

P is the power rating

V is the potential difference across the resistor

R is the resistance

If the maximum power rating is $P=5.0 W$ , and the resistance of the resistor is $R=15 k\Omega = 15000 \Omega$ , then we can find the maximum potential difference across the resistor by re-arranging the previous equation for V:

$V=\sqrt{PR}=\sqrt{(5.0 W)(15000 \Omega)}=273.9 V$

(b) 1.6 W

In this case, we have:

$R=9.0 k\Omega = 9000 \Omega$ is the resistance of the resistor

$V=120 V$ is the potential difference across the resistor

So we can find the power rating by using the same formula of part (a):

$P=\frac{V^2}{R}=\frac{(120 V)^2}{9000 \Omega}=1.6 W$

(c) Maximum voltage: 14.1 V; Rate of heat: 2.00 W and 3.00 W

Here we have two resistors of

$R_1 = 100 \Omega\\R_2 = 150 \Omega$

and each resistor has a power rating of

P = 2.00 W

So the greatest potential difference allowed in the first resistor is

$V=\sqrt{PR_1}=\sqrt{(2.00 W)(100 \Omega)}=14.1 V$

While the greatest potential difference allowed in the second resistor is

$V=\sqrt{PR_2}=\sqrt{(2.00 W)(150 \Omega)}=17.3 V$

So the greatest potential difference allowed not to overheat either of the resistor is 14.1 V.

In this condition, the power dissipated on the first resistor is 2.00 W, while the power dissipated on the second resistor is

$P_2 = \frac{V^2}{R_2}=\frac{(14.1 V)^2}{150 \Omega}=1.33 W$

And this corresponds to the rate of heat generated in the first resistor (2.00 W) and in the second resistor (1.33 W).

4 0

3 years ago

Given that y is the vertical displacement of a wave at anytime and A is the amplitude of the wave, w is the angular speed of the

denis-greek [22]

Explanation:

The general equation describing a wave is:

y(x,t) = A sin(kx - wt)

Let's say that for a particular wave on a string the equation is:

y(x,t) = (0.9 cm) sin[(1.2 m-1)x - (5.0 s-1)t]

(a) Determine the wave's amplitude, wavelength, and frequency.

(b) Determine the speed of the wave.

(c) If the string has a mass/unit length of m = 0.012 kg/m, determine the tension in the string.

(d) Determine the direction of propagation of the wave.

(e) Determine the maximum transverse speed of the string.

Solutions

Part (a): The wave's amplitude, wavelength, and frequency can be determined from the equation of the wave:

y(x,t) = (0.9 cm) sin[(1.2 m-1)x - (5.0 s-1)t]

The amplitude is whatever is multiplying the sine.

A = 0.9 cm

The wavenumber k is whatever is multiplying the x:

k = 1.2 m-1The wavelength isl=2pk= 5.2 m

The angular frequency w is whatever is multiplying the t.

w = 5.0 rad/sf=w2p= 0.80 Hz

Part (b): The wave speed can be found from the frequency and wavelength:

v = f l = 0.80 * 5.2 = 4.17 m/s

Part (c): With m = 0.012 kg/m and the wave speed given by:v=(Tm)½

This gives a tension of T = m v2 = 0.012 (4.17)2 = 0.21 N.

Part (d): To find the direction of propogation of the wave, just look at the sign between the x and t terms in the equation. In our case we have a minus sign:

y(x,t) = (0.9 cm) sin[(1.2 m-1)x - (5.0 s-1)t]

A negative sign means the wave is traveling in the +x direction.

A positive sign means the wave is traveling in the -x direction.

Part (e): To determine the maximum transverse speed of the string, remember that all parts of the string are experiencing simple harmonic motion. We showed that in SHM the maximum speed is:

vmax = Aw

In this case we have A = 0.9 cm and w = 5.0 rad/s, so:

vmax = 0.9 * 5.0 = 4.5 cm/s

maybe this should help

6 0

3 years ago