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
Delicious77 [7]
3 years ago
14

A roller coaster car is elevated to a height of 30 m and released from rest to roll along a track. At a certain time T it is at

a height of 2 m and has lost 25.000 J of energy to friction. The car has a mass of 800 kg. Answer the following questions. (a) How fast is the car going at time T? (b) How fast would the car be going at time T if the track were frictionless?
Physics
1 answer:
Naddika [18.5K]3 years ago
4 0

Explanation:

Initial energy = final energy + work done by friction

PE = PE + KE + W

mgH = mgh + 1/2 mv² + W

(800)(9.8)(30) = (800)(9.8)(2) + 1/2 (800) v² + 25000

v = 22.1 m/s

Without friction:

PE = PE + KE

mgH = mgh + 1/2 mv²

(800)(9.8)(30) = (800)(9.8)(2) + 1/2 (800) v²

v = 23.4 m/s

You might be interested in
A 2kg block has 70J of KE. It then travels 1.5 meters up a hill. As it travels up the hill friction does -12J of work on the blo
Dima020 [189]

Answer:

v = 5.34[m/s]

Explanation:

In order to solve this problem, we must use the theorem of work and energy conservation. This theorem tells us that the sum of the mechanical energy in the initial state plus the work on or performed by a body must be equal to the mechanical energy in the final state.

Mechanical energy is defined as the sum of energies, kinetic, potential, and elastic.

E₁ = mechanical energy at initial state [J]

E_{1}=E_{pot}+E_{kin}+E_{elas}\\

In the initial state, we only have kinetic energy, potential energy is not had since the reference point is taken below 1.5[m], and the reference point is taken as potential energy equal to zero.

In the final state, you have kinetic energy and potential since the car has climbed 1.5[m] of the hill. Elastic energy is not available since there are no springs.

E₂ = mechanical energy at final state [J]

E_{2}=E_{kin}+E_{pot}

Now we can use the first statement to get the first equation:

E_{1}+W_{1-2}=E_{2}

where:

W₁₋₂ = work from the state 1 to 2.

E_{k}=\frac{1}{2} *m*v^{2} \\

E_{pot}=m*g*h

where:

h = elevation = 1.5 [m]

g = gravity acceleration = 9.81 [m/s²]

70 - 12 = \frac{1}{2}*2*v^{2}+2*9.81*1.5

58 = v^{2} +29.43\\v^{2} =28.57\\v=\sqrt{28.57}\\v=5.34[m/s]

4 0
3 years ago
Un satélite geoestacionario se encuentra a una distancia de 120.000 km sobre la superficie de Júpiter. Determine: a. El periodo
Lisa [10]

Answer:

a) a geostationary satellite is that it is always at the same point with respect to the planet,

b) f = 2.7777 10⁻⁵ Hz

c)                           d)   w = 1.745 10⁻⁴ rad / s

Explanation:

a) The definition of a geostationary satellite is that it is always at the same point with respect to the planet, that is, its period of revolutions is the same as the period of the planet

  •                T = 10 h (3600 s / 1h) = 3.6 104 s

b) the period the frequency are related

                T = 1 / f

                 f = 1 / T

                 f = 1 / 3.6 104

                 f = 2.7777 10⁻⁵ Hz

c) the distance traveled by the satellite in 1 day

The distance traveled is equal to the length of the circumference

                 d = 2pi (R + r)

                 d = 2pi (69 911 103 + 120 106)

                 d = 1193.24 m

d) the angular velocity is the angle traveled between the time used.

                 .w = 2pi /t

                  w = 2pi / 3.6 10⁴

                  w = 1.745 10⁻⁴ rad / s

how fast is

                  v = w r

                  v = 1.75 10-4 (69.911 106 + 120 106)

                  v = 190017 m / s

5 0
3 years ago
A toy plane is flying in a horizontal circle by being attached to a 0.75 meter string. The plane has a mass of 101.7 grams and m
nadezda [96]

Answer:

F = 2,894 N

Explanation:

For this exercise let's use Newton's second law

      F = m a

The acceleration is centripetal

     a = v² / r

Angular and linear variables are related.

     v = w r

Let's replace

     F = m w² r

The radius r and the length of the rope is related

    cos is = r / L

    r = L cos tea

Let's replace

    F = m w² L cos θ

Let's reduce the magnitudes to the SI system

     m = 101.7 g (1 kg / 1000g) = 0.1017 kg

      θ = 5 rev (2π rad / rev) = 31,416 rad

     w =  θ / t

     w = 31.416 / 5.1

     w = 6.16 rad / s

     F = 0.1017 6.16² 0.75 cos  θ

     F = 2,894 cos  θ

The maximum value of F is for  θ equal to zero

     F = 2,894 N

7 0
3 years ago
William Ferrel:
balu736 [363]

Answer:

William Ferrel created a tide-prediction machine.

Explanation:

  • William Ferrel create a machine in late 19th century that was the best combination of mechanical parts and computer coding.
  • It was a mechanical analog computer that could predict the ebb of tides and even the height of tides that could be irregular.
  • It was widely used for marine networks and navigation. Later on many improvisations and additional features were added on it.
  • During the world war times, this tide prediction machine was of great use for military purpose.
3 0
3 years ago
Which statement best describes air pressure at high altitudes? (Points : 3)
WARRIOR [948]
Air pressure decreases as altitude increases. this is because air pressure is caused by the gravity of earth, the gravity pulls on the air, compacting it and making a pressure.
But as we go higher, gravity decreases, causing less pull on the air resulting in less air pressure.<span />
5 0
3 years ago
Read 2 more answers
Other questions:
  • How does the tide cycle affect erosion along a sea coast?
    5·1 answer
  • What is the G.P.E of 675 newtons on 26000 meter mountain
    11·1 answer
  • This subject is MUSIC, but there is no MUSIC subject to pick in the "pick a subject " bar, so I just picked a random one...Sorry
    7·1 answer
  • A 700- kg vehicle is traveling at the speed of 6m/s how much kinetic energy does it have ???
    8·2 answers
  • When you are paddling a canoe, you push the water backwards with your paddle, witch in turn will push you forward. Witch law of
    5·1 answer
  • A softball with a mass of 0.11 kg goes moves at a speed of 12 m/s, then the ball is hit by a bat and rebounds in the opposite di
    7·1 answer
  • A ball rolls off the edge of a table with a fairly large horizontal velocity. Which of the following statements are true? (Selec
    5·1 answer
  • What are the three most influential variables that affect electrical force?
    13·1 answer
  • A hockey stick stores 4.2 J of potential energy when it is bent 3.1 cm. Treating the hockey stick as a spring, what is its sprin
    14·1 answer
  • A 100 Ohm, 200 Ohm, and 400 Ohm resistors are in parallel with each other. What is the equivalent
    6·2 answers
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!