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
Usimov [2.4K]
3 years ago
9

To a good approximate, the only external force that does work on a cyclist moving on level ground is the force of air resistance

. Suppose a cyclist is traveling at 15 km/h on level ground. Assume he is using 480 W of metabolic power.
a. Estimate the amount of power he uses for forward motion.
b. How much force must he exert to overcome the force of air resistance?
Physics
1 answer:
mart [117]3 years ago
3 0

Answer:

a. 120 W

b. 28.8 N

Explanation:

To a good approximate, the only external force that does work on a cyclist moving on level ground is the force of air resistance. Suppose a cyclist is traveling at 15 km/h on level ground. Assume he is using 480 W of metabolic power.

a. Estimate the amount of power he uses for forward motion.

b. How much force must he exert to overcome the force of air resistance?

(a) He is 25% efficient, therefore the cyclist will be expending 25% of his power to drive the bicycle forward

Power = efficiency X metabolic power

= 0.25 X 480

= 120 W

(b)

power if force times the velocity

P = Fv

convert  15 km/h to m/s

v = 15 kmph = 4.166 m/s

F = P/v

= 120/4.166

= 28.8 N

definition of terms

power is the rate at which work is done

force is that which changes a body's state of rest or uniform motion in a straight line

velocity is the change in displacement per unit time.

You might be interested in
By means of a rope whose mass is negligible, two blocks are suspended over a pulley, as the drawing shows. The pulley can be tre
tankabanditka [31]

Answer:

Mass of the pull is 77 kg

Explanation:

Here we have for

Since  the rope moves along with pulley, we have

For the first block we have

T₁ - m₁g = -m₁a = -m₁g/4

T₁ =  3/4(m₁g) = 323.4 N

Similarly, as the acceleration of the second block is the same as the first block but in opposite direction, we have

T₂ - m₂g = m₂a = m₂g/4

T₂ =  5/4(m₂g) = 134.75 N

T₂r - T₁r = I·∝ = 0.5·M·r²(-α/r)

∴ M = -\frac{2}{a} (T_2-T_1)

M = -\frac{2}{2.45} (134.75-323.4) = 77 \, kg

Mass of the pull = 77 kg.

5 0
3 years ago
(11%) Problem 5: A submarine is stranded on the bottom of the ocean with its hatch 25 m below the surface. In this problem, assu
V125BC [204]

Answer:

F = 1.24*10^4 N

Explanation:

Given

Depth of the ship, h = 25 m

Density of water, ρ = 1.03*10^3 kg/m³

Diameter of the hatch, d = 0.25 m

Pressure of air, P(air) = 1 atm

Pressure of water =

P(w) = ρgh

P(w) = 1.03*10^3 * 9.8 * 25

P(w) = 2.52*10^5 N/m²

P(net) = P(w) + P(air) - P(air)

P(net) = P(w)

P(net) = 2.52*10^5 N/m²

Remember,

Pressure = Force / Area, so

Force = Area * Pressure

Area = πr² = πd²/4

Area = 3.142 * 0.25²/4

Area = 3.142 * 0.015625

Area = 0.0491 m²

Force = 0.0491 * 2.52*10^5

F = 12373 N

F = 1.24*10^4 N

5 0
3 years ago
Read 2 more answers
Find the volume of a rectangular prism that is 8m long, 4m wide, and 300cm high
konstantin123 [22]
  • L=8m
  • B=4m
  • H=300cm=3m

\\ \bull\tt\longmapsto Volume=LBH

\\ \bull\tt\longmapsto Volume=8(4)(3)

\\ \bull\tt\longmapsto Volume=96m^3

6 0
2 years ago
Read 2 more answers
The Earth and Moon are separated by about 4.0 10^6 m. Suppose Mars is [{MathJax fullWidth='false' 2.9 \times 10^{11} }] m from E
Shalnov [3]

Answer:

a) α=7.9x10^-4 rad

b) θ=1.12x10^-4 rad

c) The Earth and the Moon cannot be seen without a telescope.

Explanation:

In this exercise we will use the concepts of angular resolution, which depends on both the wavelength of the rays and the diameter of the eye or lens on the meter. Its unit of measure is the radian. The attached image shows the solution step by step.

4 0
2 years ago
What 3 things do you need to make an electromagnet ?
Hunter-Best [27]

Answer:

1. Battery

2. Copper wire

3. Nail or piece of metal (zinc, iron, or steel).

5 0
2 years ago
Read 2 more answers
Other questions:
  • Why is evaporation of water greater in summer?
    15·2 answers
  • A ball of mass 0.220 kg that is moving with a speed of 6.3 m/s collides head-on and elastically with another ball initially at r
    8·1 answer
  • Which terms describes elements with different atomic masses due to varying numbers of neutrons?
    14·2 answers
  • hen a series combination of two capacitors is connected to a 12 V battery, 173 of energy is drawn from the battery. If one of th
    9·2 answers
  • A +15 nC point charge is placed on the x axis at x = 1.5 m, and a -20 nC charge is placed on the y axis at y = -2.0m. What is th
    8·1 answer
  • Which portion of the electromagnetic spectrum is used to identify fluorescent minerals?
    5·1 answer
  • Qualitative observation requires numerous data to discribe research A .true B. False
    9·1 answer
  • Describe the speed and acceleration of the ball released from the top of the track shown in the figure below
    13·1 answer
  • Potassium loses electrons when it reacts with oxygen. Which statement is true of potassium in this reaction? A. It reduces. B. I
    10·1 answer
  • Can you answer this math homework? Please!
    12·1 answer
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!