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3 years ago

3. A 92 kg Tarzan is holding on to a level 22m vine. He swings on the vine. What will his speed at the bottom of the swing be?

1 answer:

6 0

To solve this problem, we must always remember that energy is conserved. In this case, since he is falling down, he has highest potential energy at the top and zero at bottom. While his kinetic energy is zero at the top since he started from rest and highest at the bottom. We can also say that Potential Energy lost is Kinetic Energy gained thus,

- ΔPE = ΔKE ---> one is negative since PE is losing energy

- m g (h2 – h1) = 0.5 m (v2^2 – v1^2)

Where,

m = mass of tarzan (cancel that out)

g = gravitational acceleration

h2 = height at the bottom= 0

h1 = height at top = 22 m

v2 = velocity at the bottom

v1 = velocity at top = 0 (started from rest)

Therefore substituting all values:

- 9.8 (- 22) = 0.5 (v2^2)

v2 = 20.77 m / s (ANSWER)

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An electric motor rotating a workshop grinding wheel at a rate of 151 rev/min is switched off. Assume constant angular decelerat

tamaranim1 [39]

Answer:

Explanation:

Initial angular velocity ω₀ = 151 x 2π / 60

= 15.8 rad /s

final velocity = 0

Angular deceleration α = 2.23 rad / s

ω² = ω₀² - 2 α θ

0 = 15.8² - 2 x 2.23 θ

= 55.99 rad

one revolution = 2π radian

55.99 radian = 55.99 / 2 π no of terns

= 9 approx .

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3 years ago

The table below shows a sample wavelength of each type of electromagnetic radiation, along with its frequency and energy.

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Answer:

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3 years ago

If a ball with an original velocity of zero is dropped from a tall structure and it takes 7 seconds to hit the ground, what velo

Colt1911 [192]

The velocity of the ball when it reaches the ground is equal to B. 68.6 m/s. This value was obtained from the formula Vf = Vi + at. Vf is the final velocity. Vi is the initial velocity. The acceleration is "a", while the time of travel is "t". The solution is:

<span>Vf = Vi + at
</span>Vf = 0 + (-9.8 m/s^2) (7 s)
Vf = -68.6 m/s

The negative sign denotes the direction of the ball.

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3 years ago

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If the tension of the cable is 25.0 N what is the mass of the ball

marysya [2.9K]

Answer:576

Explanation:

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3 years ago

The angle between the two force of magnitude 20N and 15N is 60 degrees (20N force being horizontal) determine the resultant in m

BARSIC [14]

A) The resultant force is 30.4 N at $25.3^{\circ}$

B) The resultant force is 18.7 N at $43.9^{\circ}$

Explanation:

In order to find the resultant of the two forces, we must resolve each force along the x- and y- direction, and then add the components along each direction to find the components of the resultant.

The two forces are:

$F_1 = 20 N$ at $0^{\circ}$ above x-axis

$F_2 = 15 N$ at $60^{\circ}$ above y-axis

Resolving each force:

$F_{1x}=F_1 cos \theta = (20)(cos 0)=20 N\\F_{1y}=F_1 sin \theta =(20)(sin 0)=0 N$

$F_{2x}=F_2 cos \theta = (15)(cos 60)=7.5 N\\F_{2y}=F_2 sin \theta =(15)(sin 60)=13.0 N$

So, the components of the resultant are:

$F_x = F_{1x}+F_{2x}=20+7.5 = 27.5 N\\F_y = F_{1y}+F_{2y}=0+13.0=13.0 N$

And the magnitude of the resultant is:

$F=\sqrt{F_x^2+F_y^2}=\sqrt{27.5^2+13.0^2}=30.4 N$

And the direction is:

$\theta=tan^{-1}(\frac{F_y}{F_x})=tan^{-1}(\frac{13.0}{27.5})=25.3^{\circ}$

In this case, the 15 N is applied in the opposite direction to the 20 N force. Therefore we need to re-calculate its components, keeping in mind that the angle of the 15 N force this time is

$\theta=180^{\circ}-60^{\circ}=120^{\circ}$