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Natali5045456 [20]
3 years ago
11

Fiora starts riding her bike at 18 mi/h. After a while, she slows down to 12 mi/h, and maintains that speed for the rest of the

trip. The whole trip of 69 miles takes her 4.5 hours. For how long did she travel at 18 mi/h?
Physics
1 answer:
lord [1]3 years ago
4 0

Answer:

t = 2.5 hours

Explanation:

given,

speed of the bike for t time= 18 mi/h

final speed of the bike after t time = 12 mi/h

total distance, D = 69 miles

total time, T= 4.5 hour

time for which speed of the bike is 18 mi/h = ?

we know distance = speed x time

now,

18 x t + 12 (4.5 - t) = 69

6 t + 54 = 69

6 t = 15

t = 2.5 hours

The bike was at the speed of 18 mi/h for 2.5 hours.

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In an inelastic collision, as compared to an elastic collision, what is to be expected?.
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The loss or conservation of kinetic energy is the difference between an elastic and an inelastic collision. Kinetic energy is not preserved in an inelastic collision, and it will change forms into sound, heat, radiation, or another form. The kinetic energy in an elastic collision is preserved and does not change forms.
3 0
2 years ago
A 50 kg child runs off a dock at 2.0 ms (horizontally) and lands in a waiting rowboat of mass 150 kg. At what speed does the row
Alex73 [517]

Answer:

The boat moves away from the dock at 0.5 m/s.

Explanation:

Hi there!

Since no external forces are acting on the system boy-boat at the moment at which the boy lands on the boat, the momentum of the system is conserved (i.e. it remains constant).

The momentum of the system is calculated as the sum of the momentum of the boy plus the momentum of the boat. Before the boy lands on the boat, the momentum of the system is given by the momentum of the boy.

momentum of the system before the boy lands on the boat:

momentum of the boy + momentum of the boat

m1 · v1 + m2 · v2 = momentum of the system

Where:

m1 and v1: mass and velocity of the boy.

m2 and v2: mass and velocity of the boat.

Then:

50 kg · 2.0 m/s + 150 kg · 0 m/s = momentum of the system

momentum of the system = 100 kg m/s

After the boy lands on the boat, the momentum of the system will be equal to the momentum of the boat moving with the boy on it:

momentum of the system = (m1 + m2) · v (where v is the velocity of the boat).

100 kg m/s = (50 kg + 150 kg) · v

100 kg m/s / 200 kg = v

v = 0.5 m/s

The boat moves away from the dock at 0.5 m/s.

5 0
3 years ago
Why do smaller endotherms require more energy per unit of mass than larger endotherms?
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They expend more oxygen. Littler endotherms lose warmth to the earth proportionately speedier than huge endotherms: less warm mass, protecting layers in littler creatures are less successful by dint of being more slender, and more prominent surface region to volume proportion implies snappier radiation of warmth
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3 years ago
A _____ is used in a motor to switch the direction of the magnetic field created by the current.
insens350 [35]

Answer:

A _commutator_ is used in a motor to switch the direction of the magnetic field created by the current.

The rotating part of a motor that holds the electromagnets is called the __armature___.

Electric current passes through the _brushes_ and into the electromagnets in an electric motor.

A motor turns _electrical_ energy into _mechanical_ energy.

Explanation:

A commutator, which is a split ring rotary switching device, reverses the direction of the current between the external circuit and the rotor. Reversing the current reverses the magnetic field.

The armature comprises the rotating part of the motor and the electromagnets

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8 0
3 years ago
An electron in a TV picture tube is accelerated through a potential difference of 10 kV before it hits the screen. What is the k
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Answer:

10,000 eV

Explanation:

According to the law of conservation of energy, the kinetic energy gained by the electron is equal to its change in electric potential energy:

K=\Delta U=q \Delta V

where:

K is the kinetic energy of the electron

q=1 e is the magnitude of the charge of the electron

\Delta V is the potential difference through which the electron has been accelerated

For this electron in the TV, we have

\Delta V=10 kV=10000 V

Therefore, the kinetic energy of the electron in electronvolts is

K=(1 e)(10000 V)=10000 eV

7 0
3 years ago
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