# Physics

A cyclist starts from rest and coasts down a 6.5∘{\rm ^\circ} hill. The mass of the cyclist plus bicycle is 95kg{\rm kg} . The cyclist has traveled 270m{\rm m} .What was the net work done by gravity on the cyclist? How fast is the cyclist going? Ignore air resistance.

1. 👍 0
2. 👎 0
3. 👁 1,432
1. Note:
the degree symbol is written as
& d e g ;
(suppress all spaces)

Difference in elevation, Δh
= 270m × sin(6.5°)
total mass (cyclist + bicycle), m
= 95 kg
total weight
= mg

Work done (on cyclist & bicycle)
=mgΔh

Component of force along slope, F
= mg cos(θ)
downward acceleration along slope, a
= F/m
= g cos(θ)

Consider the acceleration over distance d of 270 m
d=270 m
vi=0 (initial velocity)
vf (final velocity)
a=gcos(θ)
θ=6.5°
g=9.8 m/s²
m=95 kg

We can apply the kinematics equation
to solve for vf.

1. 👍 1
2. 👎 0
2. a=gsin(theta) not gcos(theta)

1. 👍 2
2. 👎 0

## Similar Questions

1. ### physic

Starting from rest, a car accelerates at 2.5 m/s^2 up a hill that is inclined 5.4 ^\circ above the horizontal. how far the car travel horizontally in 15s?

asked by Anonymous on July 2, 2011
2. ### physics

A skier is accelerating down a 30.0 degrees hill at 1.80m/s^2. How long will it take her to reach the bottom of the hill, assuming she starts from rest and accelerates uniformly, if the elevation change is 375 m? Apparently the

asked by Mika on July 21, 2011
3. ### physics

A sled slides without friction down a small, ice-covered hill. If the sled starts from rest at the top of the hill, its speed at the bottom is 7.60 m/s. What is the height of the hill?

asked by uknown person on December 4, 2017
4. ### Physics

Assume that all of the mass of a bicycle wheel is concentrated at its rim. Such a wheel of mass 1.2 kg and radius 30 cm starts from rest at the top of a hill 100m long and inclined at 20 degrees to the horizontal. What will be the

asked by kelsey on March 25, 2014
5. ### Physics

A cyclist approaches the bottom of a gradual hill at a speed of 20 m/s. The hill is 4.4 m high, and the cyclist estimates that she is going fast enough to coast up and over it without peddling. Ignoring air resistance and

asked by Zach on February 25, 2008
1. ### maths

Two cyclists start biking from a trail's start 3 hours apart. The second cyclist travels at 10 miles per hour and starts 3 hours after the first cyclist who is traveling at 6 miles per hour. How much time will pass before the

asked by thommini on February 20, 2010
2. ### Physics

A bicyclist is coasting straight down a hill at a constant speed. The mass of the rider and bicycle is 55.0 kg, and the hill is inclined at 16.0° with respect to the horizontal. Air resistance opposes the motion of the cyclist.

asked by Kelsey on October 25, 2011
3. ### physics

A child and sled with a combined mass of 50.0 kg slide down a frictionless slope. If the sled starts from rest and has a speed of 3.40 m/s at the bottom, what is the height of the hill?

asked by Allie on March 9, 2011
4. ### Physics

A bicyclist is coasting straight down a hill at a constant speed. The mass of the rider and bicycle is 85.0 kg, and the hill is inclined at 19.0° with respect to the horizontal. Air resistance opposes the motion of the cyclist.

asked by Lauren on February 3, 2011
5. ### Physics

A cyclist approaches the bottom of a gradual hill at a speed of 20 m/s. The hill is 4.4 m high, and the cyclist estimates that she is going fast enough to coast up and over it without peddling. Ignoring air resistance and

asked by Zach on February 25, 2008