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3 years ago

Why would scientist use both relative and absolute dating

1 answer:

6 0

Well, relative dating is the science determining the relative order of past events like the age of an object compared to another object without determining the absolute age. The absolute age is the process of determining an age on a specific chronology in archeology and geology. Some scientists prefer the terms chromatic or calendar dating, as the word absolute implies an unwarranted certainty or accuracy. Hope I helped

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Block B is attached to a massless string of length L = 1 m and is free to rotate as a pendulum. The speed of block A after the c

Amanda [17]

Complete Question

The diagram for this question is shown on the first uploaded image

Answer:

The minimum velocity of A is $v_A= 4m/s$

Explanation:

From the question we are told that

The length of the string is $L = 1m$

The initial speed of block A is $u_A$

The final speed of block A is $v_A = \frac{1}{2}u_A$

The initial speed of block B is $u_B = 0$

The mass of block A is $m_A = 7kg$ gh

The mass of block B is $m_B = 2 kg$

According to the principle of conservation of momentum

$m_A u_A + m_B u_B = m_Bv_B + m_A \frac{u_A}{2}$

Since block B at initial is at rest

$m_A u_A = m_Bv_B + m_A \frac{u_A}{2}$

$m_A u_A - m_A \frac{u_A}{2} = m_Bv_B$

$m_A \frac{u_A}{2} = m_Bv_B$

making $v_B$ the subject of the formula

$v_B =m_A \frac{u_A}{2 m_B}$

Substituting values

$v_B =\frac{7 u_A}{4}$

This $v__B$ is the velocity at bottom of the vertical circle just at the collision with mass A

Assuming that block B is swing through the vertical circle(shown on the second uploaded image ) with an angular velocity of $v__B'$ at the top of the vertical circle

The angular centripetal acceleration would be mathematically represented

$a= \frac{v^2_{B}'}{L}$

Note that this acceleration would be toward the center of the circle

Now the forces acting at the top of the circle can be represented mathematically as

$T + mg = m \frac{v^2_{B}'}{L}$

Where T is the tension on the string

According to the law of energy conservation

The energy at bottom of the vertical circle = The energy at the top of

the vertical circle

This can be mathematically represented as

$\frac{1}{2} m(v_B)^2 = \frac{1}{2} mv^2_B' + mg 2L$

From above

$(T + mg) L = m v^2_{B}'$

Substitute this into above equation

$\frac{1}{2} m(\frac{7 v_A}{4} )^2 = \frac{1}{2} (T + mg) L + mg 2L$

$\frac{49 mv_A^2}{16} = \frac{1}{2} (T + mg) L + mg 2L$

$\frac{49 mv_A^2}{16} = T + 5mgL$

The value of velocity of block A needed to cause B be to swing through a complete vertical circle is would be minimum when tension on the string due to the weight of B is zero

This is mathematically represented as

$\frac{49 mv_A^2}{16} = 5mgL$

making $v_A$ the subject

$v_A = \sqrt{\frac{80mgL}{49m} }$

substituting values

$v_A = \sqrt{\frac{80* 9.8 *1}{49} }$

$v_A= 4m/s$

6 0

3 years ago

A large man sits on a four-legged chair with his feet off the floor. The combined mass of the man and chair is 95.0 kg. If the c

Leto [7]

Answer:

Pressure, $P=29.6\times 10^5\ Pa$

Explanation:

It is given that,

Combined mass of the man and the chair, m = 95 kg

Radius of the leg of chair, r = 0.5 cm = 0.005 m

A large man sits on a four-legged chair with his feet off the floor. The force acting per unit area is called the pressure exerted.

$P=\dfrac{F}{A}$

$P=\dfrac{mg}{A}$

Area of 4 legs, A = 4 A

$P=\dfrac{mg}{4\pi r^2}$

$P=\dfrac{95\times 9.8}{4\pi (0.005)^2}$

$P=29.6\times 10^5\ Pa$

So, the pressure each leg exert on the floor is $29.6\times 10^5\ Pa$ . Hence, this is the required solution.

7 0

3 years ago

A billiard ball moving at 0.5 m/s strikes another identical billiard ball, which is at rest, in an elastic head-on collision on

NikAS [45]

Answer: assuming that the billiard balls are of identical weight the impacted billiard ball will move forward at around 0.5m/s (not considering energy conservation). The ball impacting the 2nd one would stop because most of its Kinetic energy would have been transferred into the not moving ball.

Explanation: hope this helps!

4 0

3 years ago

What is 6.02 x 10^4 in standard notation

Vesnalui [34]

I believe you mean 6.02*10^7 but you want to shift the decimal 7 times to the right which would be 60200000 (:

4 0

2 years ago

Which of the following can be thought of as either a wave or a particle?

IrinaK [193]

Both matter and light have been demonstrated to exhibit wave-like and particle-like behavior.

Light as a wave: light can diffract & refract

Light as a particle: photoelectric effect, Compton scattering

Matter as a wave: Davisson-Germer experiment

Matter as a particle: find a picture of any kinematics problem in a high school physics textbook

Choice D

7 0

3 years ago