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polet [3.4K]
3 years ago
7

A biker pedals hard to ride his bike to the top of a 44 m hill. He decides to let his bike coast down the hill, and is having so

much fun coasting that he decided not to pedal even climbing the next hill. If that hill is 10 m high, what will the biker s speed be at the top of that hill?
Physics
1 answer:
Dafna11 [192]3 years ago
6 0

Answer:

The bikers speed at the top of other hill is <u>25.82 m/s.</u>

Explanation:

Considering the biker is riding on a frictionless surface.

∴ There is no non-conservative or external force acting on the biker.

Hence we can conserve the energy of biker and bike as a system.

Let,

h_{1} = 44m

h_{2} = 10m

Since the biker starts from rest , his initial speed v_{1} = 0 m/s

Let final speed of the bike at the top of other hill be v_{2}.

∴ Initial Energy (at the top of 44m hill) = mgh_{1}

  Final Energy  (at the top of 10m hill) =  mgh_{2} + \frac{1}{2}mv_{2} ^{2}.

Conserving both the energies , we get

mgh_{1} = mgh_{2} + \frac{1}{2}mv_{2} ^{2}

∴ v_{2} = \sqrt{2g(h_{1}-h_{2} )}

Substituting the values for g , h_{1} , h_{2} , we get

v_{2} = 25.82 m/s

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Mary takes 6.0 seconds to run up a flight of stairs that is 102 meters long. If Mary's weight is 87 newtons, what power has Mary
fredd [130]

Answer: 1479watts

Explanation:

Power is defined as the energy expended or work done in a specific time.

Mathematically,

Power = Workdone/time taken

Since work done is force × distance

Power = force × distance/time

Force = Mary's weight = 87N

Distance = height of the flight = 102meters

Time = 6.0seconds

Substituting in the formula we have;

Power = 87 × 102/6

Power = 1,479watts

Note that the time must be in seconds before usage. If its given in minutes, you will have to convert to seconds

8 0
3 years ago
A particle of mass m moves under an attractive central force F(r) = -Kr4 with angular momentum L. For what energy will the motio
docker41 [41]

Answer:

Angular velocity is same as frequency of oscillation in this case.

ω = \sqrt{\frac{7K}{m} } x [\frac{L^{2}}{mK}]^{3/14}

Explanation:

- write the equation F(r) = -Kr^{4} with angular momentum <em>L</em>

- Get the necessary centripetal acceleration with radius r₀ and make r₀ the subject.

- Write the energy of the orbit in relative to r = 0, and solve for "E".

- Find the second derivative of effective potential to calculate the frequency of small radial oscillations. This is the effective spring constant.

- Solve for effective potential

- ω = \sqrt{\frac{7K}{m} } x [\frac{L^{2}}{mK}]^{3/14}

3 0
3 years ago
As you take your leisurely tour through the solar system, you come across a 1.45 kg rock that was ejected from a collision of as
nikklg [1K]

Answer:

1.3310\times 10^8 m/s is the rock's speed.

Explanation:

Momentum is defined as motion possessed by the moving body's mass. Mathematically it a product of mas and velocity of the body.

Momentum(P)=Mass(m)\times velocity(v)

Given : Mass of rock = m = 1.45 kg

Velocity of the rock = v

Momentum of the rock = P =1.93\times 10^8 kg m/s

1.93\times 10^8 kg m/s=1.45 kg\times v

v=\frac{1.93\times 10^8 kg m/s}{1.45 kg}=1.33\times 10^8 m/s

1.3310\times 10^8 m/s is the rock's speed.

6 0
3 years ago
Puck 1 (1 kg) travels with velocity 20 m/s to the right when it collides with puck 2 (1 kg) which is initially at rest. After th
Burka [1]

Answer:

Explanation:

Parameters given:

Mass of Puck 1, m = 1 kg

Mass of Puck 2, M = 1 kg

Initial velocity of Puck 1, u = 20 m/s

Initial velocity of Puck 2, U = 0 m/s

Final velocity of Puck 1, v = 5 m/s

Since we are told that momentum is conserved, we apply the principle of conservation of momentum:

Total initial momentum of the system = Total final momentum of the system

mu + MU = mv + MV

(1 * 20) + (1 * 0) = (1 * 5) + (1 * V)

20 = 5 + V

V = 20 - 5 = 15 m/s

Puck 2 moves with a velocity of 15 m/s

7 0
3 years ago
Please Help Fast!!!
S_A_V [24]
Aluminum has an atomic number of 13,  so it has 13 protons. In its natural state, it does not have a charge,  so it has an equal amount of electrons, 13. The atomic mass of aluminum is approximately 27. Since protons and neutrons make up that mass, and each of the particles are around 1 atomic mass unit, if there are 13 protons, then there are 27-13 neutrons, or 14 neutrons. So the first answer choice is correct.
6 0
3 years ago
Read 2 more answers
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