Answer:
so initial speed of the rock is 30.32 m/s
correct answer is b. 30.3 m/s
Explanation:
given data
h = 15.0m
v = 25m/s
weight of the rock m = 3.00N
solution
we use here work-energy theorem that is express as here
work = change in the kinetic energy ..............................1
so it can be written as
work = force × distance ...................2
and
KE is express as
K.E = 0.5 × m × v²
and it can be written as
F × d = 0.5 × m × (vf)² - (vi)² ......................3
here
m is mass and vi and vf is initial and final velocity
F = mg = m (-9.8) , d = 15 m and v{f} = 25 m/s
so put value in equation 3 we get
m (-9.8) × 15 = 0.5 × m × (25)² - (vi)²
solve it we get
(vi)² = 919
vi = 30.32 m/s
so initial speed of the rock is 30.32 m/s
Answer:
<em>60008.4 J</em>
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Explanation:
The mass of each kid = 30 kg
mass of the cart = 20 kg
The speed of the cart down the hill = 30 km/hr = 30 x 1000/3600 = 8.33 m/s
The height of the hill = 80 m
The potential energy of the boys at the top of the hill = mgh
where
m is the total mass of the kids and the cart = (30 x 2) + 20 = 80 kg
g is the acceleration due to gravity = 9.81 m/s^2
h is their height above the ground = 80 m (on the top of the hill)
substituting, we have
potential energy PE = 80 x 9.81 x 80 = 62784 J
At an instance at the bottom of the hill
their kinetic energy = 
where
v is their velocity = 8.33 m/s
m is their total mass = 80 kg
substituting, we have
kinetic energy KE = 
= 2775.6 J
Total work done on the cart is equal to the energy lost by the cart when it reached the bottom of the hill
work done by friction = PE - KE = 62784 - 2775.6 = <em>60008.4 J</em>
Answer:
Explanation:
The resulting valie would be too large
Answer:
Explanation:
Ruler. A steel ruler aids the measurement and layout of straight lines. The ruler, also called "straightedge" or "straight-edged ruler," is a long, thin strip of wood, metal or plastic marked with increments of measurement.
Measuring Tape. The modern measuring tape's roughly palm-sized casing contains a coiled strip of metal marked with increments of measurement. The metal strip, called "tape," attaches to a spring which automatically retracts the tape into the casing following use.
Walking Tape Measure. The walking tape measure, also called "surveyor's measure," records the distance traveled by a wheel. An operator pushes the measure's wheel, similar to a bicycle wheel, by a handle as an attached ticker box displays feet or meters in the same format as a car's odometer.
Laser Measure. The laser measure offers point and shoot distance measurement. In its most basic form, a laser measure is a hand-held electronic device with a digital display.
