mikebarton Posted March 20, 2013 Share Posted March 20, 2013 Hello, So here's the question? If a 50kg cart and a 30kg cart were both left to run downhill using no force other than that of gravity which would reach the bottom first? (Assuming both cars are released at the same time on a hill) And likewise with this, if the two cars were connected with a central pin, if the pin was removed, would the 50kg car accelerate past the 30kg car assuming it was the front car? Thanks for your help! Link to comment Share on other sites More sharing options...
Strix Posted March 20, 2013 Share Posted March 20, 2013 nope, sorry, that doesn't work. There's a friction/resistance force Drop them from the sky and they fall at the same rate Link to comment Share on other sites More sharing options...
mikebarton Posted March 20, 2013 Author Share Posted March 20, 2013 Thanks Greatly appreciated! Link to comment Share on other sites More sharing options...
maxmaximus Posted March 20, 2013 Share Posted March 20, 2013 They would reach the bottom together. Link to comment Share on other sites More sharing options...
illuminati Posted March 21, 2013 Share Posted March 21, 2013 The 50kg cart would have more friction as it would press into the ground more so the 30kg cart would win the race. Link to comment Share on other sites More sharing options...
Obelix Posted March 21, 2013 Share Posted March 21, 2013 Assuming no other force retards them like friction, air resistance etc they will accelerate at the same rate and reach the bottom at the same time. This is the experiment that Galileo did (he didn't drop things of the tower in Pisa he rolled a cannonball anda wooden ball of the same size down a hill as I recall) With such similar masses as yours the difference in air resistance, and in rolling resistance are going to be so small that they will sensibly be about the same anyway, but as others have said the 50kg mass will probably have just a little more rolling resistance and will be a little bit slower, assuming that they were the same material. If you had a steel 50kg mass and a wood 30kg mass then the steel one would probably have less rolling resistance for example... Link to comment Share on other sites More sharing options...
Alcoblog Posted March 21, 2013 Share Posted March 21, 2013 Assuming no other force retards them like friction, air resistance etc they will accelerate at the same rate and reach the bottom at the same time. This is the experiment that Galileo did (he didn't drop things of the tower in Pisa he rolled a cannonball anda wooden ball of the same size down a hill as I recall) Jeez ... that makes you out to be over 350 years old! Is this a record or are there any older posters on SF? Link to comment Share on other sites More sharing options...
Lockjaw Posted March 21, 2013 Share Posted March 21, 2013 nope, sorry, that doesn't work. There's a friction/resistance force Drop them from the sky and they fall at the same rate Nope, sorry, that doesn't work. There's a friction/resistance force. Drop them on the Moon and they fall at the same rate. Link to comment Share on other sites More sharing options...
shanes teeth Posted March 21, 2013 Share Posted March 21, 2013 Nope, sorry, that doesn't work. There's a friction/resistance force. Drop them on the Moon and they fall at the same rate. No,I'm sorry,it does work.Despite it being over 40 years ago I clearly remember our physics teacher "Rocker" Rodgers holding in outstreched arms a tennis ball and a cricket ball,letting them go at the same time and them both hitting the floor at the same time.It was like witnessing witchcraft! Either the laws of physics have changed since then(decimalisation?) or there really was no atmosphere in Mr Rodgers physics lessons! Link to comment Share on other sites More sharing options...
truman Posted March 21, 2013 Share Posted March 21, 2013 No,I'm sorry,it does work.Despite it being over 40 years ago I clearly remember our physics teacher "Rocker" Rodgers holding in outstreched arms a tennis ball and a cricket ball,letting them go at the same time and them both hitting the floor at the same time.It was like witnessing witchcraft! Either the laws of physics have changed since then(decimalisation?) or there really was no atmosphere in Mr Rodgers physics lessons! He needed to try and drop them from higher up or in a different medium.oil for example.....you won't see the difference over a height of only 2 metres... if everything fell at the same rate then why do objects have different terminal velocities? Terminal Velocity is expressed as Vt=sqrt (2mg over pACd) Vt is the terminal velocity, m is the mass of the falling object, g is gravitational acceleration at the Earth's surface, Cd is the drag coefficient, ρ is the density of the fluid the object is falling through, and A is the object's cross-sectional area. This takes into account most of the factors affecting a falling object.. Link to comment Share on other sites More sharing options...
Recommended Posts
Archived
This topic is now archived and is closed to further replies.