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Sunny_sXe [5.5K]
3 years ago
14

If a 4.5 kg object is dropped from a height of 6.0 m, what will be its velocity when it is halfway toward the ground? (Use g = 9

.80 m/s2, and ignore air resistance.) 7.7 m/s 11 m/s 16 m/s 29 m/s
Physics
2 answers:
dangina [55]3 years ago
7 0
When an object falls or is dropped from rest it's initial velocity is zero.
Using the equations for a motion in straight line. I can find the time it takes to reach 3.0 m down (half way).
x = vt - 4.9t²
-3 = 0 - 4.9t²
-3/-4.9 = t²
0.6122 = t²
0.7825 sec = t

v = v - gt
v = 0 - 9.8(0.7825)
v = -7.67 m/s
the negative denotes downward direction.

You  could also solve the problem using potential and kinetic energy.

Since it starts with maximum PE and gets converted to KE when it hits the ground. mgh = mv²/2
mass cancels, use 3 meters for the halfway distance
-9.8(-3) = v²/2
29.4 * 2 = v²
√(58.8) = 7.67 m/s downwards
notsponge [240]3 years ago
6 0

Answer:

7.7 rounded

Explanation:

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Assume that at sea-level the air pressure is 1.0 atm and the air density is 1.3 kg/m3.
scoundrel [369]

Answer

Pressure, P = 1 atm

air density, ρ = 1.3 kg/m³

a) height of the atmosphere when the density is constant

   Pressure at sea level = 1 atm = 101300 Pa

   we know

   P = ρ g h

   h = \dfrac{P}{\rho\ g}

   h = \dfrac{101300}{1.3\times 9.8}

          h = 7951.33 m

height of the atmosphere will be equal to 7951.33 m

b) when air density decreased linearly to zero.

  at x = 0  air density = 0

  at x= h   ρ_l = ρ_sl

 assuming density is zero at x - distance

 \rho_x = \dfrac{\rho_{sl}}{h}\times x

now, Pressure at depth x

dP = \rho_x g dx

dP = \dfrac{\rho_{sl}}{h}\times x g dx

integrating both side

P = g\dfrac{\rho_{sl}}{h}\times \int_0^h x dx

P =\dfrac{\rho_{sl}\times g h}{2}

 now,

h=\dfrac{2P}{\rho_{sl}\times g}

h=\dfrac{2\times 101300}{1.3\times 9.8}

  h = 15902.67 m

height of the atmosphere is equal to 15902.67 m.

6 0
3 years ago
A 900-kg car cruising at a constant speed of 60 km/h is to accelerate to 100 km/h in 4 s. The additional power needed to achieve
kiruha [24]

To solve this problem we will apply the concepts related to power as a function of the change of energy with respect to time. But we will consider the energy in the body equivalent to kinetic energy. The change in said energy will be the difference between the two velocity data given by half of the mass. We will first convert the given units into an international system like this

Initial Velocity,

V_i = 60km/h (\frac{1000m}{1km})(\frac{1h}{3600s})

V_i = 16.6667m/s

Final Velocity,

V_f = 100km/h (\frac{1000m}{1km})(\frac{1h}{3600s})

V_f = 27.7778m/s

Now Power is defined as the change of Energy over the time,

P = \frac{E}{t}

But Energy is equal to Kinetic Energy,

P = \frac{\frac{1}{2} m\Delta v^2}{t}

P = \frac{\frac{1}{2} m(v_f^2-v_i^2)}{t}

Replacing,

P = \frac{\frac{1}{2} (900)(27.7778^2-16.6667^2)}{4}

P = 56kW

Therefore the correct answer is A.

8 0
3 years ago
Weight is measured with a ___________. <br> Question 4 options: <br> A. Balance <br> B. Scale
kap26 [50]

Answer: B

Explanation: Scale

4 0
3 years ago
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What is the energy of an electromagnetic wave that has a frequency of 5.0 x 10⁵ Hz?
Valentin [98]

Answer: 3.3 x 10^-28 J

Explanation: just answered on a quiz!! :)

5 0
3 years ago
A very bouncy ball is dropped from a height of 2.47 m to an asphalt playground surface and the height of its 4 th bounce is meas
goldfiish [28.3K]

Answer:

0.912

Explanation:

Given that

Height of bouncing of the ball, h = 1.71 m

Number of times the ball bounced, n = 4 times

Height from which the ball was dropped, H = 2.47

First, let's start by defining what coefficient of restitution means

Coefficient of Restitution, CoR is the "ratio of the final to initial relative velocity between two objects after they collide. It normally ranges from 0 to 1 where 1 would be a perfectly elastic collision."

It is mathematically represented as

CoR = (velocity after collision) / (velocity before collision)

1.71 = 2.47 * c^4, where c = CoR

1.71/2.47 = c^4

c^4 = 0.6923

c = 4th root of 0.6923

c = 0.912

6 0
4 years ago
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