A bicycle rider has a speed of 19.0 m/s at a height of 55.0 m above sea level when he begins coasting down hill. The mass of the rider and his bike is 88.0 kg. Sea level is the zero level for measuring gravitational potential energy. Ignoring friction and air resistance, what is the rider’s total mechanical energy when he coasts to a height of 25.0 m above sea level?
So I tried to use this equation:
ME = .5(mv^2) + mgh
=.5(88*19^2) + 88(9.8)(55-25)
and got 4.18 × 10^4 J
but that was incorrect.. the hint they gave me was "This answer accounts for kinetic energy but incorrectly combines it with the change in gravitational potential energy..."
What am I doing wrong? Any help would be awesome.
Thanks, 10 points to most help.
Answers are...
4.74 × 104 J
4.18 × 104 J
1.59 × 104 J
6.33 × 104 J
So I tried to use this equation:
ME = .5(mv^2) + mgh
=.5(88*19^2) + 88(9.8)(55-25)
and got 4.18 × 10^4 J
but that was incorrect.. the hint they gave me was "This answer accounts for kinetic energy but incorrectly combines it with the change in gravitational potential energy..."
What am I doing wrong? Any help would be awesome.
Thanks, 10 points to most help.
Answers are...
4.74 × 104 J
4.18 × 104 J
1.59 × 104 J
6.33 × 104 J