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Nitella [24]
3 years ago
12

A penny is dropped from the top of a building that is 300.0 m tall. Calculate the speed of the penny as it hits the ground. (met

ers per second please)
Physics
1 answer:
Sauron [17]3 years ago
3 0

We have the equation of motion s = ut + \frac{1}{2} at^2, where s is the displacement, a is the acceleration, u is the initial velocity and t is the time taken.

Here s = 300 m, u = 0 m/s, a = 9.81 m/s^2

Substituting

   300 = 0*t+\frac{1}{2} *9.8*t^2\\ \\ 4.9t^2 = 300\\ \\ t =7.82 seconds

Now we have v = u+at, where v is the final velocity

Here u = 0 m/s, a= 9.81 m/s^2 and t = 7.82 seconds

Substituting

     v = 0+9.8*7.82 = 76.68 m/s

The speed with which the penny strikes the ground = 76.68 m/s.

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A diver rises quickly to the surface from a 5.0 m depth. If she did not exhale the gas from her lunds before rising, by what fac
Inessa [10]

Answer:

1.5 times

Explanation:

h = depth of the diver initially = 5 m

\rho = density of seawater = 1030 kg m⁻³

P_{i} = Initial pressure at the depth

P_{f} = final pressure after rising = 101325 Pa

Initial pressure at the depth is given as

P_{i} = P_{f} + \rho gh\\P_{i} = 101325 + (1030) (9.8) (5)\\P_{i} = 151795 Pa

V_{i} = Initial volume at the depth

V_{f} = Final volume after rising

Since the temperature remains constant, we have

P_{f} V_{f} = P_{i} V_{i}\\(101325) V_{f} = (151795) V_{i}\\V_{f} = 1.5 V_{i}

6 0
3 years ago
A girl stand 5m away from a large plane mirror.How far must she walk ti be 2m away from her image?​
KonstantinChe [14]

Answer:

3m

Explanation:

If a girl is 5m away from a mirror, she needs to walk a further 3m to be 2m away from her image.

5m-3m = 2m

4 0
1 year ago
Two identical point charges of +Q coul are separated by a distance of 10 cm.
tatiyna

Answer:

IM NOT SMART

Explanation:

5 0
3 years ago
A cylinder contains 250 L of hydrogen gas (H2) at 0.0^∘Cand a pressure of 10.0 atm. How much energy is required to raise the tem
Over [174]

Answer:

The amount of energy needed to raise the temperature of the cylinder by 25 °C is 23.3 KJ of heat.

Explanation:

The step by step calculation can be found in the attachment below. Thank you.

8 0
2 years ago
A 4-lb ball b is traveling around in a circle of radius r1 = 3 ft with a speed (vb)1 = 6 ft>s. if the attached cord is pulled
Leya [2.2K]
Position #1:
radius, r₁ = 3 ft
Tangential speed, v₁ = 6 ft/s

By definition, the angular speed is
ω₁ = v₁/r₁ = (3 ft/s) / (3 ft) = 1 rad/s

Position #2:
Radius, r₂ = 2 ft

By definition, the moment of inertia in positions 1 and 2 are respectively
I₁ = (4 lb)*(3 ft)² = 36 lb-ft²
I₂ = (4 lb)*(2 ft)² = 16 lb-ft²

Because momentum is conserved,
I₁ω₁ = I₂ω₂
Therefore the angular velocity in position 2 is
ω₂ = (I₁/I₂)ω₁
      = (36/16)*1 = 2.25 rad/s
The tangential velocity in position 2 is
v₂ = r₂ω₂ = (2 ft)*(225 rad/s) = 4.5 ft/s

At each position, there is an outward centripetal force.
In position 1, the centripetal force is
F₁ = m*(v²/r₂) = (4)*(6²/3) = 48 lbf
In position 2, the centripetal force is
F₂ = (4)*(4.5²/2) = 40.5 lbf

The radius diminishes at a rate of 2 ft/s.
Therefore the force versus distance curve is as shown below.

The work done is the area under the curve, and it is
W = (1/2)*(48.0+40.5 ft)*(3-2 ft) = 44.25 ft-lb

Answer:  44.25 ft-lb


6 0
3 years ago
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