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AfilCa [17]
3 years ago
15

A person kicks a rock horizontally off a cliff with a speed of 35m/s. It takes 12 seconds to hit the ground below(don’t forget y

our units). What is the height of the cliff? What is the final vertical velocity? What is the range?
Physics
1 answer:
Marta_Voda [28]3 years ago
4 0

take gravity g as 9.81

height of cliff = ut +1/2at^2 = 1/2*(9.81)*12^2 = 706.32 meters

What is the final vertical velocity

v=u+at, final velocity v = 0 + 9.81*12 = 117.72 m/s


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During their physics field trip to the amusement park, Leslie and Maria took a ride on the Whirligig. The Whirligig ride consist
grandymaker [24]

Answer:

a) frequency = 0.1724 Hz

b) Period = 5.8 sec

c) speed = 7.04 m/s

d) acceleration = 7.62 m/s²

Explanation:

Given that;

radius = 6.5m

time period = 5.8 sec every circle

a)  the frequency

frequency is the number of rotation in unit time

frequency = 1 / time period = 1/5.8

frequency = 0.1724 Hz

b)  the period

period is time taken in one rotation

period = total time / rotation = 5.8 / 1

Period = 5.8 sec

c)  the speed

speed = distance/time = circumference/time period = 2πr / t = (2π×6.5) / 5.8

speed = 7.04 m/s

d) acceleration

To find the acceleration we take the linear velocity squared divided by the radius of the circle.

so

acceleration = v² / r = (7.04)² / 6.5 = 49.5616 / 6.5

acceleration = 7.62 m/s²

6 0
3 years ago
5–111. A box having a weight of 8 lb is moving around in a circle of radius rA = 2 ft with a speed of (vA)1 = 5 ft>s while co
Elis [28]

Answer:

a) vB = 10.77 ft/s

b) W = 11.30 lb*ft

Explanation:

a) W = 8 lb   ⇒  m = W/g = 8 lb/32.2 ft/s² = 0.2484 slug

vA <em>lin</em> = 5 ft/s

rA = 2 ft

v <em>rad</em> = 4 ft/s

vB = ?

rB = 1 ft

W = ?

We can apply The law of conservation of angular momentum

L<em>in</em> = L<em>fin</em>

m*vA*rA =  m*vB*rB    ⇒    vB = vA*rA / rB

⇒   vB = (5 ft/s)*(2 ft) / (1 ft) = 10 ft/s  (tangential speed)

then we get

vB = √(vB tang² + vB rad²)   ⇒   vB = √((10 ft/s)² + (4 ft/s)²)

⇒   vB = 10.77 ft/s

b) W = ΔK = K<em>B</em> - K<em>A</em> = 0.5*m*vB² - 0.5*m*vA²

⇒     W = 0.5*m*(vB² - vA²) = 0.5*0.2484 slug*((10.77 ft/s)²-(5 ft/s)²)

⇒     W = 11.30 lb*ft

6 0
3 years ago
Riley is doing an experiment working with friction. He wants to find two ways to modify an object that could increase or decreas
Dmitrij [34]
If the type of friction is sliding friction, it may be increased by increasing the roughness of the surface and may be decreased by smoothing the surface or applying a lubricant.
8 0
3 years ago
Read 2 more answers
How much force is required to move a sled 5 meters if a person uses 60 J of work?
Brut [27]
W=F*S

W - Work
F - Force
S - Distance (from latin word 'spatium)

so...
S= 5 (m)
W=60 (J)

W=F*S
F=W/S
F=60/5=12 J/m = 12 N (Newtons)


6 0
3 years ago
The electric output of a power plant is 716 MW. Cooling water is the main way heat from the powerplant is rejected, and it flows
Stels [109]

Answer:

(a) 83475 MW

(b) 85.8 %

Explanation:

Output power = 716 MW = 716 x 10^6 W

Amount of water flows, V = 1.35 x 10^8 L = 1.35 x 10^8 x 10^-3 m^3

mass of water, m = Volume  x density = 1.35 x 10^8 x 10^-3 x 1000

                                                               = 1.35 x 10^8 kg

Time, t = 1 hr = 3600 second

T1 = 25.4° C, T2 = 30.7° C

Specific heat of water, c = 4200 J/kg°C

(a) Total energy, Q = m x c x ΔT

Q = 1.35 x 10^8 x 4200 x (30.7 - 25.4) = 3 x 10^12 J

Power = Energy / time

Power input = P = \frac{3 \times 10^{12}}{3600}=8.35 \times 10^{8}W

Power input = 83475 MW

(b) The efficiency of the plant is defined as the ratio of output power to the input power.

\eta =\frac{Power output}{Power input}

\eta =\frac{716}{83475}=0.858

Thus, the efficiency is 85.8 %.

7 0
3 years ago
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