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3 years ago

7

Is radioactive decay used to determine absolute or relative age?

1 answer:

jeka943 years ago

4 0

Radioactive decay is used to determine absolute age.

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A helicopter carrying Dr. Evil takes off with a constant upward acceleration of 5.0 m/s2. Secret agent Austin Powers jumps on ju

denpristay [2]

Answer:

a) $h=250\ m$

b) $\Delta h=0.0835\ m$

Explanation:

Given:

upward acceleration of the helicopter, $a=5\ m.s^{-2}$

time after the takeoff after which the engine is shut off, $t_a=10\ s$

a)

<u>Maximum height reached by the helicopter:</u>

using the equation of motion,

$h=u.t+\frac{1}{2} a.t^2$

where:

u = initial velocity of the helicopter = 0 (took-off from ground)

t = time of observation

$h=0+0.5\times 5\times 10^2$

$h=250\ m$

b)

time after which Austin Powers deploys parachute(time of free fall), $t_f=7\ s$

acceleration after deploying the parachute, $a_p=2\ m.s^{-2}$

<u>height fallen freely by Austin:</u>

$h_f=u.t_f+\frac{1}{2} g.t_f^2$

where:

$u=$ initial velocity of fall at the top = 0 (begins from the max height where the system is momentarily at rest)

$t_f=$ time of free fall

$h_f=0+0.5\times 9.8\times 7^2$

$h_f=240.1\ m$

<u>Velocity just before opening the parachute:</u>

$v_f=u+g.t_f$

$v_f=0+9.8\times 7$

$v_f=68.6\ m.s^{-1}$

<u>Time taken by the helicopter to fall:</u>

$h=u.t_h+\frac{1}{2} g.t_h^2$

where:

$u=$ initial velocity of the helicopter just before it begins falling freely = 0

$t_h=$ time taken by the helicopter to fall on ground

$h=$ height from where it falls = 250 m

now,

$250=0+0.5\times 9.8\times t_h^2$

$t_h=7.1429\ s$

From the above time 7 seconds are taken for free fall and the remaining time to fall with parachute.

<u>remaining time,</u>

$t'=t_h-t_f$

$t'=7.1428-7$

$t'=0.1428\ s$

<u>Now the height fallen in the remaining time using parachute:</u>

$h'=v_f.t'+\frac{1}{2} a_p.t'^2$

$h'=68.6\times 0.1428+0.5\times 2\times 0.1428^2$

$h'=9.8165\ m$

<u>Now the height of Austin above the ground when the helicopter crashed on the ground:</u>

$\Delta h=h-(h_f+h')$

$\Delta h=250-(240.1+9.8165)$

$\Delta h=0.0835\ m$

5 0

2 years ago

A roller coaster track is 3000 meters long. It takes 100 seconds to travel once around the roller coaster. What is the average s

Svetllana [295]

All you have to do is divide 3000 by 100, Its 30

6 0

3 years ago

Read 2 more answers

Given a force of 88n and an acceleration of 4m/s2 what is the mass?

Hitman42 [59]

F=ma
m=F/a = 88/4 = 22 kg

5 0

2 years ago

Read 2 more answers

Which of the following statements is true about scientific theories?

artcher [175]

<span>d. scientific theories summarize patterns found in nature

Hope this helps!</span>

5 0

2 years ago

A conducting rod moves perpendicularly through a uniform magnetic field. How does the emf change if the magnetic field is increa

Marysya12 [62]

Answer:

c) It increases by a factor of 8

Explanation:

According to Faraday's law (and Lenz' law), the induced EMF is given as the rate of change of magnetic flux.

Mathematically:

V = -dФ/dt

Magnetic flux, Ф, is given as:

Ф = BA

where B = magnetic field strength and A = Area of object

Hence, induced EMF becomes:

V = -d(BA)/dt or -BA/t

If the magnetic field is increased by a factor of 4, ( $B_n = 4B$ ) and the time required for the rod to move is decreased by a factor of 2 ( $t_n = t/2$ ), the induced EMF becomes:

$V_n = -(B_nA)/t_n$

$V_n = \frac{-4BA}{(t/2)}\\\\V_n = \frac{-8BA}{t} \\\\V_n = 8V\\$

The EMF has increased by a factor of 8.

5 0

2 years ago