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4 years ago

Why does an archeogist carry out an excavation

1 answer:

7 0

<span>Archaeologists carry out excavations in order to collect data that they eventually analyze to learn more about the past.</span>

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A 40 kg girl and an 8.4 kg sled are on the surface of a frozen lake, 15 m apart. By means of a rope, the girl exerts a 5.2 N for

stealth61 [152]

Answer:

(a) $a_s=0.62\frac{m}{s^2}$

(b) $a_s=0.13\frac{m}{s^2}$

Explanation:

(a) According to Newton's second law, the acceleration of a body is directly proportional to the force exerted on it and inversely proportional to it's mass.

$a_s=\frac{F}{m_s}\\a_s=\frac{5.2N}{8.4kg}\\a_s=0.62\frac{m}{s^2}$

(b) According to Newton's third law, the force that the sled exerts on the girl is equal in magnitude but opposite in the direction of the force that the girl exerts on the sled:

$a_g=\frac{F}{m_g}\\a_g=\frac{5.2N}{40kg}\\a_g=0.13\frac{m}{s^2}$

$x_f=x_0+v_0t \pm \frac{at^2}{2}$

For the girl, we have $x_0=0$ and $v_0=0$ . So:

$x_f_g=\frac{a_gt^2}{2}(1)$

For the sled, we have $v_0=0$ . So:

$x_f_s=x_0_s-\frac{a_st^2}{2}(2)$

When they meet, the final positions are the same. So, equaling (1) and (2) and solving for t:

$x_0_s-\frac{a_st^2}{2}=\frac{a_st^2}{2}\\t^2(a_g+a_s)=2x_0_s\\t=\sqrt{\frac{2x_s_0}{a_g+a_s}}\\t=\sqrt{\frac{2(15m)}{0.13\frac{m}{s^2}+0.62\frac{m}{s^2}}}\\t=6.32s$

Now, we solve (1) for $x_f_g$

$x_f_g=\frac{0.13\frac{m}{s^2}(6.32s)^2}{2}\\x_f_g=2.6m\\x_f=2.6m$

5 0

3 years ago

Moving a magnet quickly in and out of a coil of wire produces _____.

Oksanka [162]

<span>An electric current.</span>

8 0

4 years ago

A car rounds a curve while maintaining a constant speed. Is there a net force on the car as it rounds the curve?

Nesterboy [21]

Answer:

Yes, Centripetal Force acts on the Car.

Explanation:

When a car undergoes a circular motion, a centripetal force acts onto it.

Centripetal Force = [m*(v^2)]/R , where

R is the radius of curve
v is the constant speed
m is the mass of the car

4 0

4 years ago

Two gliders move toward each other on a linear air track, which we assume is frictionless. Glider A has a mass of 0.50 kg, and g

Nataly_w [17]

Answer:

-0.4 m/s

-3.552 m/s

Explanation:

$m_1$ = Mass of first glider = 0.5 kg

$m_2$ = Mass of second glider = 0.3 kg

$u_1$ = Initial Velocity of first glider = 2 m/s

$u_2$ = Initial Velocity of second glider = -2 m/s

$v_1$ = Final Velocity of first glider

$v_2$ = Final Velocity of second glider = 2 m/s

As the linear momentum of the system is conserved we have

$m_1u_1+m_2u_2=m_1v_1+m_2v_2\\\Rightarrow v_1=\dfrac{m_1u_1+m_2u_2-m_2v_2}{m_1}\\\Rightarrow v_1=\dfrac{0.5\times 2+0.3\times (-2)-0.3\times 2}{0.5}\\\Rightarrow v_1=-0.4\ m/s$

The velocity of glider A is -0.4 m/s

$u_1$ = 0

$u_2$ = -5 m/s

$v_2$ = 0.92 m/s

$m_1u_1+m_2u_2=m_1v_1+m_2v_2\\\Rightarrow v_1=\dfrac{m_1u_1+m_2u_2-m_2v_2}{m_1}\\\Rightarrow v_1=\dfrac{0.5\times 0+0.3\times (-5)-0.3\times 0.92}{0.5}\\\Rightarrow v_1=-3.552\ m/s$

The velocity of glider A is -3.552 m/s

8 0

3 years ago

Name three ways a workout in the healthy heart zone benefits your health

babymother [125]

Peak. Intensity: Vigorous (85 to 100 percent of your max heart rate) Benefit: Increases performance speed.
Cardio. Intensity: Hard (70 to 84 percent of your max hr) Benefit: Builds cardiovascular fitness and muscle strength.
Fat Burn. Intensity: Moderate (50 to 69 percent of your max hr)

7 0

3 years ago