Calculating Sam's Jet Ski Coasting Distance and Top Speed

In summary: Then, use the equation vf^2 = vi^2 + 2a(deltaX) to find the distance traveled.In summary, the problem involves Sam, with a mass of 75 kg, skiing on jet-powered skis with a thrust of 200N and a coefficient of kinetic friction on snow of 0.10. He runs out of fuel after 10 seconds and we need to find his top speed and the distance he travels before coming to a stop. Using the equations Fnet = F(thrust) - Fk and Fnet = ma, we can find his
  • #1
kraaaaamos
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Homework Statement


Sam, whose mass is 75 kg, takes off across level snow on his jet-powered skis. The skis have a thrust of 200N and a coefficient of kinetic friction on snow of 0.10. Unfortunately, the skis run out of fuel after only 10 s.

a. What is Sam’s top speed?
b. How far has Sam traveled when he finally coasts to a stop?

Homework Equations





The Attempt at a Solution



Fnet = F(thrust) - Fk
where Fk = (coeff)mg
= (0.1)(75)(9.8)
= 73.5N
plug into Fnet = F (thrust) - Fk
= 200 - 73.5
= 126.5N

To find acceleration:
Fnet = ma
126.5 = 75 a
a = 126.5/75
a = 1.69 m/s2

To find top speed:
Vf = Vi + a (deltaT)
Vf = 0 + 1.69(10)
= 16.9m/s

to find b... i have no idea.
i knwo that:
vi would be 16.9m/s
vf would be 0m/s
i don't know what the decelleration value is for when it is coasting
and i knwo that i use the equation: Vf^2 = Vi^2 + 2a (deltaX)
wehre delta (X) is change in position (displacment)

someone help!
 
Last edited:
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  • #2
Now the frictional force is the retarding force. From that find the decelleration.
 
  • #3
In February 1955, a paratrooper fell 370 m from an airplane without being able to open his chute but happened to land in snow, suffering only minor injuries. Assume that his speed at impact was 58 m/s (terminal speed), that his mass (including gear) was 85 kg, and that the force on him from the snow was at the survivable limit of 1.2 105 N.

(a) What is the minimum depth of snow that would have stopped him safely?

?m

(b) What is the magnitude of the impulse on him from the snow?


? kg·m/s

PLEASE HELP ON THIS PROBLEM
ANY HELP ON THIS PROBLEM WILL BE GREATLY APPRECIATED
 
  • #4
Show some work in the second problem
 

1. What is the difference between thrust and kinetic friction?

Thrust is a force that propels an object or moves it in a specific direction, while kinetic friction is a force that resists the motion of an object when it is in contact with another surface.

2. How is thrust measured?

Thrust is measured in newtons (N), which is a unit of force in the International System of Units (SI). It can be calculated by multiplying an object's mass by its acceleration.

3. What factors affect the amount of thrust produced?

The amount of thrust produced depends on the mass, velocity, and direction of the object, as well as the force and efficiency of the propelling device.

4. How is kinetic friction calculated?

Kinetic friction is calculated by multiplying the coefficient of kinetic friction, which is a measure of how easily two surfaces slide against each other, by the normal force, which is the force exerted by a surface on an object.

5. How can kinetic friction be reduced?

Kinetic friction can be reduced by using lubricants between two surfaces, or by smoothing and polishing the surfaces to decrease roughness and increase smoothness.

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