A sky diver jumps out of a plane 4000 meters in the air. How fast would he

A kitten runs 24 x 10⁻² m away from its master in a straight line in 12.6 s, and then run halfway back in one-third the time. Ca

Mandarinka [93]

Answer:

1.43 × 10^-2 m/s

Explanation:

Given the following :

Distance covered away from it's master = D1 = 24×10^-2 m

Time taken to cover the distance = t1 = 12.6s

Then runs halfway back D2 =

D1/ 2 = (24× 10^-2m) / 2 = 12 ×10^-2m

Time taken =T2 = T1/3 = 12.6/3 = 4.2s

Since the kitten ran in a straight line, the it is linear :

Average speed

Linear Average Velocity:

Change in distance / change in time

(D1 - D2) / (T2 - T1)

(24 - 12)×10^-2 / (12.6 - 4.2)

(12 × 10^-2)m / 8.4s

1.4285 × 10^-2

= 1.43 × 10^-2m/s

3 0

3 years ago

Unless indicated otherwise, assume the speed of sound in air to be v = 344 m/s.A violinist is tuning her instrument to concert A

Molodets [167]

Answer:

A) 443 Hz

B) She has to loosen the string

Explanation:

A) Given;

Beat frequency;f_beat = 3 Hz

Frequency of electronically generated tone; f_e = 440 Hz

We know that formula for beat frequency is given by;

f_beat = |f1 - f2|

Now, applying it to this question, we have;

f_beat = f_v - f_e

Where f_v is frequency of the note played by the violinist

Thus, plugging in the relevant values;

3 = f_v - 440

f_v = 3 + 440

f_v = 443 Hz

B) In the concept of wave travelling in a string, the frequency is directly proportional to the square root of the force acting on the string.

Now, for the violinist to get her violin perfectly tuned to concert A from what it was when she heard the 3-Hz beats, the beat frequency will have to be zero. Which means it has to decrease by 3 Hz. For it to decrease, it means that the force applied has to decrease as we have seen that frequency is directly proportional to the square root of the force acting on the string.

Thus, she would have to loosen the string.

7 0

4 years ago

How do scientists determine the number of neutrons in an isotope of an atom? A. They find the number of protons. B. They divide

Aleks04 [339]

'D' would do the job ... When you subtract the protons from the mass,
what you have left is neutrons. (The electrons can be ignored. It takes
around 1840 electrons ! to add the mass of a single proton or neutron !)

I don't know it for a fact, but I'd be surprised if the process is really that
simple. I mean, it starts out with knowing the atomic mass, and then
knowing the number of protons in the nucleus. Each of those is a
whole complex problem in itself.

5 0

3 years ago

Read 2 more answers

Please help with this problem ASAP!!!

Alika [10]

Answer:

its point Y because the dot that represents Y is cose to s and can make a chan reaction

3 0

3 years ago

A balloon is rising vertically upwards at a velocity of 10m/s. When it is at a height of 45m from the ground, a parachute bails

harina [27]

(a) 30.9 m

Let's analyze the motion of the parachutist. Its vertical position above the ground is given by

$y=h+ut+\frac{1}{2}gt^2$

where

h = 45 m is the initial height

u = 10 m/s is the initial velocity (upward)

t is the time

g = -9.8 m/s^2 is the acceleration of gravity (downward)

Substituting t=3 s , we find the height of the parachutist when it opens the parachute:

$y=45 m+(10 m/s)(3 s)+\frac{1}{2}(-9.8 m/s^2)(3 s)^2=30.9 m$

(b) 44.1 m

Here we have to find first the height of the balloon 3 seconds after the parachutist has jumped off from it. The vertical position of the balloon is given by

y = h + ut

where

h = 45 m is the initial height

u = 10 m/s is the initial velocity (upward)

t is the time

Substituting t = 3 s, we find

y = 45 m + (10 m/s)(3 s) = 75 m

So the distance between the balloon and the parachutist after 3 s is

d = 75 m - 30.9 m = 44.1 m

(c) 8.2 m/s downward

The velocity of the parachutist at the moment he opens the parachute is:

v = u +gt

where

u = 10 m/s is the initial velocity (upward)

t is the time

g = -9.8 m/s^2 is the acceleration of gravity (downward)

Substituting t = 3 s,

v = 10 m/s + (-9.8 m/s^2)(3 s)= -19.4 m/s

where the negative sign means it is downward

After t=3 s, the parachutist open the parachute and it starts moving with a deceleration of

a =+5 m/s^2

where we put a positive sign since this time the acceleration is upward.

The total distance he still has to cover till the ground is

d = 30.9 m

So we can find the final velocity by using

$v^2-u^2 = 2ad$

where this time we have u = 19.4 m/s as initial velocity. Taking the downward direction as positive, the deceleration must be considered as negative:

a = -5 m/s^2

Solving for v,

$v=\sqrt{u^2 +2ad}=\sqrt{(19.4 m/s)^2+2(-5 m/s^2)(30.9 m)}=8.2 m/s$

(d) 5.24 s

We can find the duration of the second part of the motion of the parachutist (after he has opened the parachute) by using

$a=\frac{v-u}{t}$

where

a = -5 m/s^2 is the deceleration

v = 8.2 m/s is the final velocity

u = 19.4 m/s is the initial velocity

t is the time

Solving for t, we find

$t=\frac{v-u}{a}=\frac{8.2 m/s-19.4 m/s}{-5 m/s^2}=2.24 s$

And added to the 3 seconds between the instant of the jump and the moment he opens the parachute, the total time is

t = 3 s + 2.24 s = 5.24 s

8 0

3 years ago