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HACTEHA [7]
3 years ago
6

A driver drove for 3 hours at a certain speed. if he drove 12 more miles at the same speed, the distance would be 132 miles. at

what speed did he drive?
Physics
1 answer:
Zepler [3.9K]3 years ago
4 0

Answer:

40mph

Explanation:

1st leg DATA:

time = 3 hrs ; speed = r mph ; distance = 3r miles

------------

2nd leg DATA:

speed = r mph ; distance = 12 miles

 

--------------------------------

3r + 12 = 132

3r = 120

rate = 40 mph

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Please help.. I'm desperate.
rosijanka [135]

Answer:

Newton's Second Law tells us that the more mass an object has, the more force is needed to move it. A larger rocket will need stronger forces (eg. more fuel) to make it accelerate. The space shuttles required seven pounds of fuel for every pound of payload they carry.

Explanation:

7 0
2 years ago
Why is an object's density expressed as a relationship between two units?
vfiekz [6]
Probably for kind of the same reason that speed is expressed as a
relationship between two units.  You know, like miles per hour .

I guess the only reason is because no single unit has been invented
to describe density.

The rate of doing work or using energy would always be expressed
as a relationship between two units ... we would say that the rate of
work is "(so many) joules per second".  But the "watt" was invented,
so we can say "(so many) watts" instead.

So I guess you're right.  Density could be simpler to describe
if we only had a unit for it.  Then we wouldn't have to say "(so many)
grams per cubic centimeter".  We would just say "(so many) (new unit)".

Let's try it out:
 
"Uhhh, pardon me Professor . . . I've been working late in the lab,
and I believe I've identified a new substance, hitherto unknown to
the scientific community, and totally unexpected.  In its pure form,
the substance appears to be pink, it smells like butterscotch, and
its density is approximately 27.4 Brianas.  I think it's time we published
these findings ... with your name as lead investigator, of course."

I like it !
5 0
3 years ago
The knee extensors insert on the tibia at an angle of 30 degrees (from the longitudinal axis of the tibia), at a distance of 3 c
Reika [66]

Answer:

the knee extensors must exert 15.87 N

Explanation:

Given the data in the question;

mass m = 4.5 kg

radius of gyration k = 23 cm = 0.23 m

angle ∅ = 30°

∝ = 1 rad/s²

distance of 3 cm from the axis of rotation at the knee r = 3 cm = 0.03 m

using the expression;

ζ = I∝

ζ = mk²∝

we substitute

ζ = 4.5 × (0.23)² × 1

ζ  = 0.23805 N-m

so

from; ζ = rFsin∅

F = ζ / rsin∅

we substitute

F = 0.23805 / (0.03 × sin( 30 ° )

F = 0.23805 / (0.03 × 0.5)

F F = 0.23805 / 0.015

F = 15.87 N

Therefore, the knee extensors must exert 15.87 N

7 0
2 years ago
A truck has shock absorbers with a spring constant of 24200 N/m. When it hits a bump, it oscillates at 0.429 Hz. What is the mas
siniylev [52]

Answer:

3331.5 kg

Explanation:

Given:

Spring constant of the spring (k) = 24200 N/m

Frequency of oscillation (f) = 0.429 Hz

Let the mass be 'm' kg.

Now, we know that, a spring-mass system undergoes Simple Harmonic Motion (SHM). The frequency of oscillation of SHM is given as:

f=\frac{1}{2\pi}\sqrt{\frac{k}{m}}

Rewrite the above equation in terms of 'm'. This gives,

2\pi f=\sqrt{\frac{k}{m}}\\\\Squaring\ both\ sides,\ we\ get:\\\\(2\pi f)^2=\frac{k}{m}\\\\m=\frac{k}{4\pi^2 f^2}

Now, plug in the given values and solve for 'm'. This gives,

m=\frac{24200\ N/m}{4\pi^2\times (0.429\ Hz)^2 }\\\\m=\frac{24200\ N/m}{4\pi^2\times 0.184\ Hz^2}\\\\m\approx3331.5\ kg

Therefore, the mass of the truck is 3331.5 kg.

3 0
3 years ago
What does the principal quantum number determine?
morpeh [17]
<span>principal quantum number (n) </span>represents the relative overall energy of each orbital

Hope this helps!
4 0
2 years ago
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