A skateboarder heads down a tunnel, a distance of .8 km, after starting from rest at the top of the tunnel. Assuming a slope of 4 degrees and a frictionless surface, calculate the maximum possible speed at the end of the tunnel (a) in m/sec and (b) mph.
2007-10-09 18:08:05 · 3 answers · asked by labelapark 6 in Science & Mathematics ➔ Physics
First, assume no air resistance and no energy stored up in the skateboard wheels.
Two ways to do this, but I'm going to use energy. Potential energy at the top of the tunnel which is MGH. H is the elevation which is sin (4 degrees) *800 m or 5.58 meters. G is gravity or 10m/sec*sec or PE=M*55.8m*m/s*s.
The kinetic energy at the bottom will by 1/2 MVV. KE =PE therefore 1/2 MVV= M*55.8m*m/s*s, or
VV= 111.6 mm/ss
take the square root and
V = 10.56 m/sec
to get mph multiply by 3.3 ft/m and by 3600 sec/m and by miles/5280 ft.
therefore
V = 10.56 m/sec *3.3 ft/m *3600 sec/m *miles/5280, or
V = 23.77 ft/sec
2007-10-09 18:27:22 · answer #1 · answered by Frst Grade Rocks! Ω 7 · 1⤊ 0⤋
If there is know friction then he wont move
2007-10-09 18:17:45 · answer #2 · answered by Anonymous · 0⤊ 1⤋
Stoned on pot or not?
2007-10-09 18:10:43 · answer #3 · answered by Anonymous · 1⤊ 1⤋