Why there are not green stars?

A free-falling projectile is launched from the ground and has a hangtime of 6 seconds before hitting the ground. How high did it

grandymaker [24]

1A)

x=v0x*t=v0cosθ*t

x=52co31*3.2=142.6 m

1B)

y0=1/2gt^2-v0y*t=1/2gt^2-v0sinθt

y=0.5*9.8*3.2^2-52*sin31*3,2=23.4 m

2A)

x=2v0^2sin(2θ)/g

v0=[xg/2sin(2θ)]^1/2=14.4 m/s

the initial speed relative to the ground is

v=v0-4.4=10 m/s

2B)

fly time is

t=2voy/g

t=2*14.4/9.8=2.94

2C)

mgy=1/2mv0y^2

y=v0y^2/(2g)=10.58 m

7 0

3 years ago

The magnitude of the velocity of a projectile when it is at its maximum height above ground level is 14 m/s. (a) What is the mag

Alecsey [184]

When the projectile is at its maximum height above ground, it's at the point
of changing from rising to falling. At that exact point, its vertical speed is zero,
so the 14 m/s must be all horizontal velocity. That's not going to change.

Since we need to consider changes in vertical speed now, we need to make
some assumption about where this is all happening, so that we know the
acceleration of gravity. I'll assume that it's all happening on or near the Earth,
and the acceleration of gravity is 9.8 m/s².

I'm also going to neglect air resistance.

a). 1.2 sec before it reaches its maximum height, the projectile is rising
at a vertical speed of (1.2 x 9.8) = 11.76 m/s.
The magnitude of its velocity is

the square root of (14² + 11.76²) = 18.28 m/s, directed about 40° above horizontal.

b). 1.2 sec after it reaches its maximum height, the projectile is falling
at a vertical speed of (1.2 x 9.8) = 11.76 m/s.
The magnitude of its velocity is

the square root of (14² + 11.76²) = 18.28 m/s, directed about 40° below horizontal.

===========================

In 1.2 second before or after zero vertical speed, an object in free fall moves

   (1/2) (g) (t²) = (4.9) (1.2²) = 7.06 meters .

c). & d).
1.2 seconds before it reaches maximum height, the projectile is located at

   x = -14 m
   y = -7.06 m

e). & f).
1.2 seconds after it reaches maximum height, the projectile is located at

   x = +14 m
   y = -7.06 m .

I hope you recognize that 6 answers, plus a little bit of explanation,
all for 5 points, ain't too shabby. You made out well.

5 0

3 years ago

As a moon follows its orbit around a planet, the maximum grav- itational force exerted on the moon by the planet exceeds the min

Mars2501 [29]

The gravitational force exerted on the moon by the planet when the moon is at maximum distance $r_{max}$ is
$F_{min}=G \frac{Mm}{r_{max}^2}$
where G is the gravitational constant, M and m are the planet and moon masses, respectively. This is the minimum force, because the planet and the moon are at maximum distance.

Similary, the gravitational force at minimum distance is
$F_{max}=G \frac{Mm}{r_{min}^2}$
And this is the maximum force, since the distance between planet and moon is minimum.

The problem says that $F_{max}$ exceeds $F_{min}$ by 11%. We can rewrite this as
$F_{max}=(1+0.11)F_{min}=1.11 F_{min}$

Substituing the formulas of Fmin and Fmax, this equation translates into
$\frac{1}{r_{min}^2}=1.11 \frac{1}{r_{max}^2}$
and so, the ratio between the maximum and the minimum distance is
$\frac{r_{max}}{r_{min}}= \sqrt{ 1.11 }=1.05$

8 0

4 years ago

1200 meters is less than 1 kilometer

SashulF [63]

<span>1200 meters is less than 1 kilometer
</span>is false

4 0

4 years ago

Read 2 more answers

A wave has a wavelength of 0.02m and period of 8.0*10^-2 seconds. calculate it's speed. (showing working)

erik [133]

Answer:

$v = 0.25m/s$