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Elden [556K]
3 years ago
11

A man drops a baseball from the top of a building. If the ball is held at a height of 1m before it is dropped, and takes 6.8 sec

onds to hit the ground, how high is the building in meters? (Neglect air resistance)
Physics
1 answer:
attashe74 [19]3 years ago
3 0

To solve this problem we will apply the linear motion kinematic equations.

The equation that describes the position as a function of the initial velocity, acceleration and time is given by the relation

s = v_0 t +\frac{1}{2} at^2

Here,

v_0 = Initial velocity

t = Time

a = Acceleration, at this case due to gravity

There is not initial velocity then we have that the equation to the given time is

s = \frac{1}{2} (9.8)(6.8)^2

s = 226.8m

If the ball is held at a height of 1m before it is dropped, we have that the Building height is

h = 226.8-1

h = 225.8m

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Calculate the index of refraction for a medium in which the speed of light is 2.1x 108 m/s. The speed of light in vacuum is 3x10
strojnjashka [21]

Answer:

n = 1.42

Explanation:

The refractive index for a medium is given by the ratio of the speed of light in vacuum to the speed of light in a medium.

n=\dfrac{c}{v}\\\\n=\dfrac{3\times 10^8}{2.1\times 10^8}\\\\n = 1.42

So, the refractive index of the medium is 1.42.

5 0
3 years ago
if you stretch back a rubber band and release it, it shoots across the room. What type of energy conversion has occurr?
matrenka [14]
I believe the answer is potential energy if i remember correctly. 
8 0
3 years ago
Read 2 more answers
9. A radioisotope has a half-life of 4.50 min and an initial decay rate of 8400 Bq. What will be
Akimi4 [234]

Answer:

525 Bq

Explanation:

The decay rate is directly proportional to the amount of radioisotope, so we can use the half-life equation:

A = A₀ (½)^(t / T)

A is the final amount

A₀ is the initial amount,

t is the time,

T is the half life

A = (8400 Bq) (½)^(18.0 min / 4.50 min)

A = (8400 Bq) (½)^4

A = (8400 Bq) (1/16)

A = 525 Bq

8 0
3 years ago
A 0.900-V potential difference is maintained across a 1.5m length of 2
Daniel [21]

Answer:

I = 6.42 A

Explanation:

Given that,

Potential difference, V = 0.9 V

Length of the wire, l = 1.5 m

Area of cross section, A=0.6\ mm^2=6\times 10^{-7}\ m^2

We need to find the current in the wire. Let I is current. We can find it using Ohm's law as follows :

V = IR

Where R is the resistance of the wire

I=\dfrac{V}{R}\\\\I=\dfrac{V}{\rho \dfrac{l}{A}}\\\\I=\dfrac{0.9}{5.6\times 10^{-8}\times \dfrac{1.5}{6\times 10^{-7}}}\\\\I=6.42\ A

So, the current in the wire is 6.42 A.

3 0
3 years ago
Question 8
viktelen [127]

Answer: D(t) = 8.e^{-0.4t}.cos(\frac{\pi }{6}.t )

Explanation: A harmonic motion of a spring can be modeled by a sinusoidal function, which, in general, is of the form:

y = a.sin(\omega.t) or y = a.cos(\omega.t)

where:

|a| is initil displacement

\frac{2.\pi}{\omega} is period

For a Damped Harmonic Motion, i.e., when the spring doesn't bounce up and down forever, equations for displacement is:

y=a.e^{-ct}.cos(\omega.t) or y=a.e^{-ct}.sin(\omega.t)

For this question in particular, initial displacement is maximum at 8cm, so it is used the cosine function:

y=a.e^{-ct}.cos(\omega.t)

period = \frac{2.\pi}{\omega}

12 = \frac{2.\pi}{\omega}

ω = \frac{\pi}{6}

Replacing values:

D(t)=8.e^{-0.4t}.cos(\frac{\pi}{6} .t)

The equation of displacement, D(t), of a spring with damping factor is D(t)=8.e^{-0.4t}.cos(\frac{\pi}{6} .t).

3 0
3 years ago
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