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Kisachek [45]
2 years ago
5

David and Fiona want to know about how mass affects the motion of an object. David uses three objects with masses of 2 kg, 3 kg,

and 8 kg, writes out his procedure, and records his observations on the force needed to move the objects. Fiona is investigating three different objects using observation. What is the difference in the way they approached this question?
A. Only Fiona gathered evidence from her investigation.
B. David used scientific articles for evidence.
C. David's observations can be replicated by repeating his procedure.
D. Fiona's observations can be replicated by observing different objects.
Physics
1 answer:
Natali [406]2 years ago
8 0

Answer: the answer is D if its not i'm really sorry

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The figure below shows two forces A=15 N and B=5 N acting on an object. What is the
alexandr1967 [171]

Answer:

18.03 N

Explanation:

From the fiqure below,

Using parallelogram law of vector

R² = 15²+5²-2×5×15cos(180-60)

R² = 225+25-150cos120°

R² = 250-150(-0.5)

R² = 250+75

R² = 325

R = √325

R = 18.03 N

Hence the resultant force of the object is 18.03 N

7 0
2 years ago
Uranium-235 decays to thorium-231 with a half-life of 700 million years. When a rock was formed, it contained 6400 million urani
Dahasolnce [82]

Answer:

proof in explanation

Explanation:

First, we will calculate the number of half-lives:

n = \frac{t}{t_{1/2}}

where,

n = no. of half-lives = ?

t = total time passed = 2100 million years

t_{1/2} = half-life = 700 million years

Therefore,

n = \frac{2100\ million\ years}{700\ million\ years}\\\\n = 3

Now, we will calculate the number of uranium nuclei left (n_u):

n_u = \frac{1}{2^{n} }(total\ nuclei)\\\\n_u = \frac{1}{2^{3} }(6400\ million)\\\\n_u = \frac{1}{8}(6400\ million)\\\\n_u =  800\ million

and the rest of the uranium nuclei will become thorium nuclei (u_{th})

n_{th} = total\ nuclei - n_u\\n_{th} = 6400\ million-800\ million\\n_{th} = 5600\ million

dividing both:

\frac{n_{th}}{n_u}=\frac{5600\ million}{800\ million} \\\\n_{th} = 7n_u

<u>Hence, it is proven that after 2100 million years there are seven times more thorium nuclei than uranium nuclei in the rock.</u>

6 0
2 years ago
A shot is fired at an angle of 60 degree horizontal with Kinetic energy E. If air resistance is ignored, the K.E at the top of t
Lapatulllka [165]
I'm not sure what "60 degree horizontal" means.

I'm going to assume that it means a direction aimed 60 degrees
above the horizon and 30 degrees below the zenith. 

Now, I'll answer the question that I have invented.

When the shot is fired with speed of 'S' in that direction,
the horizontal component of its velocity is    S cos(60)  =  0.5 S ,
and the vertical component is   S sin(60) = S√3/2  =  0.866 S .  (rounded)

-- 0.75 of its kinetic energy is due to its vertical velocity.
That much of its KE gets used up by climbing against gravity.

-- 0.25 of its kinetic energy is due to its horizontal velocity.
That doesn't change. 

-- So at the top of its trajectory, its KE is 0.25 of what it had originally. 

That's  E/4 .
3 0
2 years ago
An airport has runways only 198 m long. a small plane must reach a ground speed of 39 m/s before it can become airborne. what av
Anarel [89]
S: 198 m 
v=39 m/s 
u=0
t=? 
a=?

v²=u²+2as
(39)²=(0)²+2(a)(198) 
1521=396a
1521/396=a
3.84 m/s^2 = a 

Hope I helped :) 
8 0
3 years ago
The nose of an ultralight plane is pointed south, and its airspeed indicator shows 28 m/s . the plane is in a 18 m/s wind blowin
leva [86]
<span>Here I think you have to find the velocity in x and y components where x is east and y is north
 So as air speed indicator shows the negative speed in y component and adding it in
  air speed while multiplying with the direction component we will get the velocity as velocity is a vector quantity so direction is also required
 v=-28 m/s y + 18 m/s (- x/sqrt(2) - y/sqrt(2))
 solving
  v= -12.7 m/s x-40.7 m/s y
 if magnitude of velocity or speed is required then
  speed= sqrt(12.7^2 + 40.7^2)
 speed= 42.63 m/s
 if angle is asked
  angle = arctan (40.7/12.7)
 angle = 72.67 degrees south of west</span>
6 0
3 years ago
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