Department of Energy Argonne National Laboratory Office of Science NEWTON's Homepage NEWTON's Homepage
NEWTON, Ask A Scientist!
NEWTON Home Page NEWTON Teachers Visit Our Archives Ask A Question How To Ask A Question Question of the Week Our Expert Scientists Volunteer at NEWTON! Frequently Asked Questions Referencing NEWTON About NEWTON About Ask A Scientist Education At Argonne $1
Name: Kiran
Status: other
Age: 20s
Location: N/A
Country: N/A
Date: 2000-2001


Question:
Hi,

I really appreciate the quick response. I have another question. Let us say there is no plank at all between the two supports.
       CAR --->

       ------------            ------------
                  |            |
                  |            |
                  |            |

The car at high speed (Less than light speed of course) lets say 120 MPH ,would still cross the cliff (say a distance of 10 Meter)without falling. So whether there is plank or not,The car does not seem to put weight at all during that period.(And also the effect of Air is not so much as to believe that it is flying). (I guess Kinetic energy is responsible here,But was curious to know more in detail)

What makes the car to cross the cliff without falling? And also as the speed of the car is increased the distance it crosses without falling also increases. Or in other words,Even when the car is moving with such a speed on ground,The weight on the ground should be lesser??


Replies:
The vertical component of motion is independent of the horizontal component. So, for example, a bullet fired from a perfectly horizontal rifle 2 m above a perfectly level plane will hit the plane at exactly the same time as another bullet dropped from the same height at the instant the gun is fired.

In the case of the car travelling at 120 mi/hr = 53 m/s (meters/second), it will cross the gap in a time t = d/v = 10 m/ (53 m/s) = 0.19s. In that time it will drop as far as any object released from rest.

The equation is
       2             2        2
1/2 g t = 0.5 32 ft/s (0.19 s) = 0.58 ft. = 7 inches!

I strongly recommend that you do NOT try this!

Best, Dick Plano...

PS I hope this is not too late to be of any use...

Dick Plano



Click here to return to the Physics Archives

NEWTON is an electronic community for Science, Math, and Computer Science K-12 Educators, sponsored and operated by Argonne National Laboratory's Educational Programs, Andrew Skipor, Ph.D., Head of Educational Programs.

For assistance with NEWTON contact a System Operator (help@newton.dep.anl.gov), or at Argonne's Educational Programs

NEWTON AND ASK A SCIENTIST
Educational Programs
Building 360
9700 S. Cass Ave.
Argonne, Illinois
60439-4845, USA
Update: June 2012
Weclome To Newton

Argonne National Laboratory