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3 years ago

A branch falls from a tree How fast is the branch moving after 0 28 seconds

Physics

1 answer:

egoroff_w [7]3 years ago

3 0

Answer:

c. 2.7 m/s

Explanation:

$v = a.t + v_{0}\\a = g = 9.81 m/s^{2}} \\t=0.28 s \\v_{0} = 0\\=> v = 9.81 * 0.28 = 2.74 m/s$

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The conduction velocity of an axon is determined by:

Marina86 [1]

The conduction velocity of an axon is determined by myelin sheath

thickness and internode distance.

Axon are structures in the neuron which is involved in the conduction of

impulses away from the cell body. Axons which have myelin sheath conduct

impulses faster than those without it.

Axons which have thicker myelin sheath and longer internode distance will

increase the conduction velocity of an axon and vice versa.

Read more on brainly.com/question/23488967

4 0

2 years ago

An object starts from rest, and accelerates at 2m/s2 for 10s. How far has it gone in that time

blagie [28]

Answer:

100m

Explanation:

$s = ut + \frac{1}{2} a {t}^{2}$

u=0;t=10sec;a=2m/s²

$s = 0(10) + \frac{1}{2}(2 \times {10}^{2} )$

s=10²;100m

7 0

4 years ago

The length of a certain wire is kept same while its radius is doubled. what is the new resistivity of this wire?

anastassius [24]

The text does not specify whether the resistance R of the wire must be kept the same or not: here I assume R must be kept the same.

The relationship between the resistance and the resistivity of a wire is
$\rho = \frac{AR}{L}$
where
$\rho$ is the resistivity
A is the cross-sectional area
R is the resistance
L is the wire length

the cross-sectional area is given by
$A=\pi r^2$
where r is the radius of the wire. Substituting in the previous equation ,we find
$\rho = \frac{\pi r^2 R}{L}$

For the new wire, the length L is kept the same (L'=L) while the radius is doubled (r'=2r), so the new resistivity is
$\rho' = \frac{\pi r'^2 R}{L'}= \frac{\pi (2r)^2 R}{L}=4 \frac{\pi r^2 R}{L} = 4 \rho$
Therefore, the new resistivity must be 4 times the original one.

5 0

3 years ago

Read 2 more answers

a ballistic pendulum is used to measure the speed of high-speed projectiles. A 6 g bullet A is fired into a 1 kg wood block B su

Galina-37 [17]

Answer:

(a) v-bullet = 399.04 m/s

(b) I = 2.38 kg m/s

Explanation:

(a) To calculate the initial speed of the bullet, you first take into account that the kinetic energy of both wood block and bullet, just after the bullet impacts the block, is equal to the potential gravitational energy of block and bullet when the cord is at 60° respect to the vertical.

The potential energy is given by:

$U=(M+m)gh$ (1)

U: potential energy

M: mass of the wood block = 1 kg

m: mass of the bullet = 6g = 6.0*10^-3 kg

g: gravitational constant = 9.8m/s^2

h: distance to the ground

The distance to the ground is calculate d by using the information about the length of the cord and the degrees of the cord respect to the vertical:

$h=l-lsin\theta\\\\h=2.2m-2,2m\ sin60\°=0.29m$

The potential energy is:

$U=(1kg+6*10^{-3}kg)(9.8m/s^2)(0.29m)=2.85J$

Next, the potential energy is equal to kinetic energy of the block and the bullet at the beginning of its motion:

$U=\frac{1}{2}(M+m)v^2\\\\v=\sqrt{2\frac{U}{M+m}}=\sqrt{2\frac{2.85J}{1kg+6*10^{-3}kg}}=2.38\frac{m}{s}$

Next, you use the momentum conservation law, in order to calculate the speed of the bullet before the impact:

$Mv_1+mv_2=(M+m)v$ (2)

v1: initial velocity of the wood block = 0m/s

v2: initial speed of the bullet

v: speed of bullet and block = 2.38m/s

You solve the equation (2) for v2:

$M(0)+mv_2=(M+m)v$

$v_2=\frac{M+m}{m}v=\frac{1kg+6*10^{-3}kg}{6*10^{-3}kg}(2.38m/s)\\\\v_2=399.04\frac{m}{s}$

The speed of the bullet before the impact with the wood block is 399.04 m/s

(b) The impulse is gibe by the change in the velocity of the block, multiplied by the mass of the block:

$I=M\Delta v=M(v-v_1)=(1kg)(2.38m/s-0m/s)=2.38kg\frac{m}{s}$

The impulse is 2.38 kgm/s

(c) The force on the cord after the impact is equal to the centripetal force over the block and bullet. That is:

$T=F_c=(M+m)\frac{v^2}{l}=(1.006kg)\frac{(2.38m/s)^2}{2.2m}=2.59N$

The force on the cord after the impact is 2.59N

4 0

3 years ago

suppose you got up this morning and the lightbulb in your room wouldn't come on. Use the of the scientific method to explain how

Anna007 [38]

Answer:TEP 1: State the Problem

A problem is a question to be thought about and either solved or answered. Problems surround all of us. Each day we are faced with more problems than we realize and we use the scientific method to solve them without even thinking about it.

EXAMPLE: The lamp does not come on when you flip the switch.

Your problem may be something that you observe around you or it can be determined by researching a topic and attempting to repeat an experiment of another scientist based on what you are working with.

STEP 2: Make Observations

An observation is the act of recognizing and recording something that is happening. Observing often involves the use of measurements and instruments to take measurements with.

EXAMPLE: (1) There is a light bulb. (2) The switch is in the on position.

(3)Other lights in the house are on. (4) The electrical cord is plugged in.

You make these observations based on the things you see, hear, and in other ways notice going on around you. You may also base your observations on information you found from researching the topic. Maybe you found the manual for the lamp and read about how it is supposed to work. You might have searched for information about Thomas Edison and his invention of the light bulb. These works of others are called background research.

STEP 3: Form a Hypothesis

A hypothesis is an educated guess meaning an explanation for something that happens based on facts that can then be tested to try and find logical answers.

EXAMPLE: The light bulb is burned out.

Your hypothesis should answer your question of why the lamp does not come on. You can come to this conclusion based on your own knowledge or from researching how a lamp works. We assume that if the lamp is plugged in and turned on that it should light. We also know that if other lights in the house are on, some electricity is running through the house. Your hypothesis does not have to be proven correct by your experiment, it just needs to be testable.

Having more than one hypothesis is fine. There could be a number of reasons why the lamp is not lit and testing them all might be the only way to find an answer. Before beginning to experiment, use logical reason to determine if any of your hypotheses can be eliminated. Maybe the fuse is blown or the outlet is bad. The switch could be wired wrong or broken. These are all testable hypotheses that could be looked into if the light bulb is not the problem.

STEP 4: Experiment

An experiment is a step-by-step procedure that is carried out under controlled conditions to attempt to prove a hypothesis, discover and unknown effect or law, or to illustrate a known law.

EXAMPLE: First remove the light bulb and screw it back in tightly to make sure that it was not loose. If that does not work, take the bulb from a lamp you know is working and place it in the broken lamp. If that lights, try another bulb to be sure.

Your experimental set-up should include a control and a variable. You may include more than one variable, but this will increase the size of your experiment. It is also very important to replicate in your experimetal procedure to avoid error. This means that you should try it at least three times. From your experiment you will need to gather data. Data can be organized in charts and or graphs and numerical data should be measured using the metric system.

The Metric System

How To Organize a Data Table

How To Graph

STEP 5: Draw a Conclusion

A conclusion is a reasonable judgment based on the examination of data from an experiment. The result or outcome of an act or process.

EXAMPLE: The lamp lit after the bulb was changed, therefore the light bulb must have been burned out.

You might also know from experience that if the filament is broken in a light bulb, it will make a rattling sound when you shake the bulb. To confirm your results, you could shake the bul

Explanation:

5 0

3 years ago