7
$\begingroup$

Could you ride a standard bicycle on the surface of mars?

Assumptions:

  • You are wearing a suit to provide life-support
  • You are riding on a prepared smooth flat martian 'road'

If you were to ride putting in the same effort on Mars as normally on Earth. Would you go faster or slower? How much faster or slower?

$\endgroup$
4
  • 4
    $\begingroup$ What physics do you think prevents it? $\endgroup$
    – Jon Custer
    May 4 at 21:53
  • $\begingroup$ @JonCuster to me the interesting part of the question is the final "Would you go faster or slower?". I give my interpretation of the question: imagine trying to ride a bike on a planet with lower gravity, would you be able to go faster than on Earth? If our fav Olympic sport were the high jump we could definitely jump higher, but how about bikers' performances? (neglecting differences due to the atmosphere and space-suit). $\endgroup$
    – Quillo
    May 5 at 10:06
  • $\begingroup$ @Quillo This is similar to the reduced 1/6th gravity on moon compared to the 1/3rd on Mars. We all have seen the video footage from the moon landings. The astronauts appear to have increased feet strength but they rather have in general slow movement specially evident when they were waving their hands. This is because absence or reduced gravity (microgravity) makes you actually to float like inside water. Your limps muscles are constantly fighting your own mass buoyancy. So I guess this is an open question. You may pedal the bike stronger but I'm not so sure if you can pedal as fast on Mars. $\endgroup$
    – Markoul11
    May 5 at 10:27
  • 1
    $\begingroup$ related but for running physics.stackexchange.com/q/707081/226902 $\endgroup$
    – Quillo
    May 5 at 12:10

3 Answers 3

5
$\begingroup$

Could you ride a standard bicycle on the surface of mars?

Yes, you could. You would balance a little differently, because the force of gravity is a little different, but the force is similar because it is still in the same direction (down, i.e., towards the center of the planet).

The main difference is that the acceleration due to gravity on Mars is about a third of what it is on Earth, so you would feel lighter, as would the bike. Also, the bike would tip slower.

You can understand this latter fact by considering a pendulum. (Balancing on a bike is similar to balancing an inverted pendulum.) For example, on earth, a pendulum of length 1 meter will swing back and forth with a period of approximately (in unit of seconds): $$ 2\pi \sqrt{1/9.8} \approx 2 $$

Or mars the pendulum period would be approximately: $$ 2\pi \sqrt{1/3.7}\approx 3.3 \;, $$ which is larger than on earth.

There would be other difference as well, for example you could spin your wheels easier on Mars, but the differences would not be insurmountable.

There are low gravity physics driving simulators that you can play with to see some of the differences. Most are built for cars, but bikes are similar except that you have to balance a bike in the transverse plane (as discussed above).

$\endgroup$
1
  • 2
    $\begingroup$ Bottom line: make sure you can fall off the bike without rupturing your suit! You'll be glad you did. $\endgroup$
    – TimWescott
    May 4 at 23:00
4
$\begingroup$

Because your question refers to a "standard bicycle" therefore assuming the bikes' tires where inflated on Earth with normal air, whatever pressure concerns:

At an altitude of 130 km Mars $CO_{2}$ atmospheric pressure is approximately 1/25 that of the Earth's atmosphere. At ground level the Martian atmosphere has a pressure of 6.518 millibars or 0.095 psi as compared to the Earth's sea level atmospheric pressure of 14.7 psi.

For a mountain bike's tire, usually inflated in Earth's conditions about at 30 psi gauge pressure (i.e. 30+14.7=44.7 psi absolute pressure), in Mars conditions it would have a pressure about 30+14.7-0.095=44.6 psi.

Therefore, a standard bicycle would most probably be fine in Martian atmosphere to answer your question although I suggest you inflate your tires with no more than 15 psi gauge pressure before taking it on Mars.

Also assuming your have maintained your muscle strength in Mars conditions you would pedal stronger.

However, this maybe similar to the reduced 1/6th gravity on moon compared to the 1/3rd on Mars. We all have seen the video footage from the moon landings. The astronauts appear to have increased feet strength but they rather have in general slow movement specially evident when they were waving their hands. This is because absence or reduced gravity (microgravity) makes you actually to float like inside water. Your limps muscles are constantly fighting your own mass inertia with less gravity assit (i.e. less gravity but the inertia remains unchanged). So I guess this is an open question. You may pedal the bike stronger but I'm not so sure if you can pedal as fast on Mars compared to Earth therefore I'm not sure If you could achieve higher speeds with the bike on Mars.

$\endgroup$
1
  • $\begingroup$ Answer was updated. $\endgroup$
    – Markoul11
    May 5 at 9:48
1
$\begingroup$

…Would you go faster or slower? How much faster or slower?

In general, the limiting speed is defined primarily by wind resistance. A steady speed will be reached when wind resistance equals the force provided by the bicyclist. If we assume the limiting speed has been reached, The cyclist will be going much faster because of the much lower wind resistance in the thin atmosphere at a given speed… although the bulk of the suit make a small difference, narrowing the margin. (I’m assuming the bike has the appropriate gears and they are used properly. Then, the effort will be efficiently translated much as on Earth, including with respect to inertia, which is not influenced by gravity.)

$\endgroup$

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.