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ratelena [41]
3 years ago
8

Which of the following is true about elements? A. Atoms of all elements contain the same number of protons, but the number of ne

utrons is different for every element. B. Atoms of all elements contain neutrons, but they do not all contain protons. C. Atoms of all elements contain electrons, but they do not all contain protons. D. Atoms of all elements contain protons, but the number of protons is different for every element.
Physics
1 answer:
DedPeter [7]3 years ago
6 0
<span>D. Atoms of all elements contain protons, but the number of protons is different for every element. </span>
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A caterpillar crawls 20 feet in 5 minutes. What is the caterpillars crawling speed?
Pavel [41]
The equation is
s= d/t

In this case you would have to write it out as:
s= 20/5
Speed = 4
6 0
3 years ago
a girl of mass 40 kg wearing high heel of radius 3mm. find the pressure exerted by her on the ground. [answer the question fast]
kakasveta [241]
You should calculate 40 kg and the radius 3mm.
7 0
3 years ago
What apparatus is used to measure salt and water <br>​
AlexFokin [52]

Answer:

Salinometer, also called salinimeter or salimeter, device used to measure the salinity of a solution. It is frequently a hydrometer that is specially calibrated to read out the percentage of salt in a solution.

Explanation:

I hope it is correct answer

7 0
2 years ago
Read 2 more answers
A 50 kg bicyclist, traveling at a speed of 12 m/s, applies the brakes, slowing her speed to 3 m/s.
Bezzdna [24]

a) Work done = Net Kinetic Energy

= 1/2 x 50 kg x ((12m/s)^2 - (3m/s)^2)

= 0.5 x 50 Kg x (144 -9)(m/s)^2

= 3375 Kg (m/s)^2

b) Force = mxa

a = 120 N/50 Kg = 2.4 m/s^2

Using newtons third law of motion, we get-

V^2 - U^2 = 2 x a x S

S= (12^2-3^2)m^2/s^2/(2 x 2.4 m/s^2)

= 28.125 m


3 0
3 years ago
A student wish to measure the gravitational acceleration g. She does it by releasing a small lead ball from rest and measures th
Goryan [66]

Answer:

(9.64 +- 0.86) m/s^2

Explanation:

The generic motion equation for constant acceleration is

x = X0 + v0 * t + \frac{1}{2}*a * t^2

Where

X0: initial position

v0: initial speed

a: acceleration

t: time

If the object has an initial speed of zero, and the frame of reference is set conveniently so that the object initial position is zero, the equation simplifies to:

x = \frac{1}{2}*a * t^2

And the acceleration can be obtained as:

a = 2*\frac{x}{t^2}

Where x is the distance fallen and a = g.

So, with the data x = (100.0 +- 0.03) mm and t = (144 +- 3) ms we can calculate

g = 2*\frac{100}{144^2} = 9.64e-3 \frac{mm}{ms^2} = 9.64 \frac{m}{s^2}

For the uncertainty we have to calculate the relative uncertainties first

For the distance (100 * 0.3)/100 = 0.3%

For the time (100 * 3)/144 = 2.08%

For multiplications or divisions the relative uncertainties are added

0.3% + 2.08% + 2.08% = 4.46%

We convert this into absolute uncertainty:

(9.64e-3 * 4.46)/100 = 0.00043 mm/(ms^2)

Finally, this is multiplied by a constant scalar, so:

2 * 0.00043 mm/(ms^2) = 0.00086 mm/(ms^2)

We convert the units

0.86 m/(s^2)

And the measurement is (9.64 +- 0.86) m/s^2

A better method is putting the ball in a ramp instead of a free fall, that way the fall is longer and the effect of time measuring uncertainty is reduced.

5 0
3 years ago
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