1answer.
Ask question
Login Signup
Ask question
All categories
  • English
  • Mathematics
  • Social Studies
  • Business
  • History
  • Health
  • Geography
  • Biology
  • Physics
  • Chemistry
  • Computers and Technology
  • Arts
  • World Languages
  • Spanish
  • French
  • German
  • Advanced Placement (AP)
  • SAT
  • Medicine
  • Law
  • Engineering
azamat
2 years ago
15

A rock falls from a vertical cliff that is 4.0 m tall and experiences no significant air resistance as it falls. At what speed w

ill it's gravitational potential energy (relative to the base of the cliff) be equal to its kinetic energy in m/s?
Physics
1 answer:
Zinaida [17]2 years ago
8 0

Answer:

v = 6.3 m/s

Explanation:

  • Since no significant air resistance exists, total mechanical energy must be kept constant at any time.
  • At the top of the cliff, all the energy is gravitational potential energy, as follows:

       E_{i}  = K_{i} + U_{i} = 0 + U_{i}  (1)

  • If we choose the ground level as our zero reference level for the gravitational potential energy, Ui is simply:
  • Ui = m*g*h (1)
  • At any height, the sum of the kinetic and the gravitational potential energy must be equal to (1).
  • We know from the question, that at the point of interest, both types of energies must be equal each other, so we can write the following expression from (1):

       m*g* h = 2*\frac{1}{2}*m*v^{2}  (2)

  • Dividing both sides by m, simplifying, and solving for v, we get:

       v = \sqrt{g*h} =\sqrt{9.8m/s2*4.0m} = 6.26 m/s (3)

  • v = 6.3 m/s (with two significative figures)
You might be interested in
1. If an object of mass m collides and velocity v collides inelastically with an object of mass 3m that is initially at rest, th
Archy [21]

Answer:

1a). 4 times. 1b) 4. 1c) 1/4.

2a) 5 times. 1b) 5 1c) 1/5

3a) 7/3 times 3b) 7/3 3c) 3/7

4a) 8/5 times 4b) 8/5 4c) 5/8

Explanation:

1) Assuming no external forces acting during the collision, total momentum must be conserved, so the following general expression applies:

m₁*v₁₀ + m₂*v₂₀ = m₁*v₁f  + m₂*v₂f (1)

If we assume that the collision is perfectly inelastic, this means that both masses stick together after the collision, so v₁f = v₂f.

If m₂ is initially at rest, ⇒ v₂₀ = 0.

Replacing in (1) we get the expression of vf as a function of v₁₀, as follows:

vf = v₁₀*(m₁/(m₁+m₂)

So, for the four cases we have the following:

1) initial mass = m

  final mass = m+3m = 4 m

⇒final mass / initial mass = 4

vf = v₀* (m/4m) = v₀/4  ⇒v₀/vf = 4

So, the velocity of the system will decrease by a factor of 4. The new velocity will be vf= v₀/4.

2) Applying the same considerations, we get:

2a)  final mass / initial mass = 5

2b) vf = v₀* (m/5m) = v₀/5  ⇒v₀/vf = 5

2c) vf = v₀/5

3) Applying the same considerations, we get:

3a)  final mass / initial mass = 7/3

3b) vf = v₀* (3m/7m) =3/7* v₀  ⇒v₀/vf = 7/3

3c) vf = 3/7*v₀

4) Applying the same considerations, we get:

4a)  final mass / initial mass = 8/5

4b) vf = v₀* (5m/8m) = 5/8*v₀ ⇒v₀/vf = 8/5

4c) vf = 5/8*v₀

3 0
3 years ago
The intensity of light depends on the amount of *blank blank*
babymother [125]

Answer:

energy? or power? I'm not really sure but using the quizzes app really help with science problems

7 0
2 years ago
At what wavelength would a star radiate the greatest amount of energy if the star has a surface temperature of 60,000 K?
kompoz [17]

Answer:

\lambda=4.81\times 10^{-8}\ m

Explanation:

We have,

The surface temperature of the star is 60,000 K

It is required to find the wavelength of a star that radiated greatest amount of energy. Wein's displacement law gives the relation between wavelength and temperature such that :

\lambda T=2.89\times 10^{-3}

Here,

\lambda = wavelength

\lambda=\dfrac{2.89\times 10^{-3}}{60000}\\\\\lambda=4.81\times 10^{-8}\ m

So, the wavelength of the star is 4.81\times 10^{-8}\ m.

7 0
2 years ago
An elephant produces a 10Hz sound wave. Assuming the speed of sound in air is 344/s, determine the wavelength of this infrasonic
user100 [1]

Answer:

34.5 m

Explanation:

Given data : An elephant produces 10 Hz sound wave. Assuming the speed of sound in air is 345 m/s. To find : What is the wavelength of sound ? Answer : The wavelength of the sound is 34.5 m.

4 0
2 years ago
What does altered mean
Elina [12.6K]
Altered means to change something.
5 0
2 years ago
Read 2 more answers
Other questions:
  • A 0.0427 kg racquet-ball is moving
    6·1 answer
  • A 2000 kg boat drifts along the waves at a velocity of 3 m/s. What is the kinetic energy of the boat?
    13·1 answer
  • During a test, a NATO surveillance radar system, operating at 12 GHz at 190 kW of power, attempts to detect an incoming stealth
    15·1 answer
  • A man pushes a heavy cart with a force exerted of 250 Newtons to keep it moving at a constant velocity. What is the kinetic fric
    14·1 answer
  • Ravens eat meat but they don’t kill it themselves. What kind of animal does this make them?
    13·1 answer
  • A 1650 kg car accelerates at a rate of 4.0 m/s^2. How much force is the car's engine producing?
    5·2 answers
  • What is elasticity in polymer generally related to?
    12·2 answers
  • Can velocity of an object be negative when it’s acceleration is positive?
    9·2 answers
  • HNO3 (aq) + H20 (1) ► NO3- (aq) + H30+ (aq)
    6·1 answer
  • Please help.<br>Just True or False​
    13·1 answer
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!