Acceleration problem?

Question

a skier starting from rest skis straight down a slope of 50. m long in 5.0 seconds. What is the magnitude of the acceleration of the skier?
thanks =D

Answer 1

You need to relate distance to acceleration. Acceleration is the second derivative of distance with respect to time. So to find an equation for distance in terms of acceleration, we integrate the acceleration twice.

The integral of acceleration is velocity, so we first have

v(t) = integral (a) dt = a*t + v_0

This says that the velocity equation equals the acceleration times time, plus a constant (which will be initial velocity).

The integral of velocity is displacement (vector distance), so we integrate v(t)

x(t) = integral (v(t)) dt = integral (a*t + v_0) dt = (1/2)a*t^2 + (v_0)*t + x_0

Since the initial velocity and initial displacement are 0, v_0 and x_0 are 0.

So

x(5 seconds) = 50 meters = (1/2)a*(5.0 seconds)^2

Solve for a.

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Edit:

My above answer assumes that acceleration is constant (which it probably is in the problem you're asked to solve - I'm guessing you're taking an intro physics course, and there are rarely non-constant accelerations in such a class).

Many others have told you that the information is incomplete. They are wrong. Assuming acceleration is constant, you don't need to know the slope of the slope, nor do you need to use gravitational acceleration.

Answer 2

4

Answer 3

Your problem is incomplete. You do not inficate the slope of the hill nor the weight of the skier. You do not indicate if the skier is using poles to influence his speed. You do not say if the only force acting on the skier is the force of gravity which is 9.8m/s direct towards the center of the Earth.

As such, the question cannot be answered.
The best one could say is the average veocity is 50/5 = 10 m/s and hence the average acceleration is 2 m/sec^2.

Answer 4

Acceleration is constant for things going downhill, equal to the magnitude of the acceleration due to gravity, which is 9.81 m/s^2

Answer 5

Speed = 10 m/s
Acceleration = 2 m/s^2

Answer 6

HAAH? uuhh eer whaat? Dis here one time I done did get tooterin from a racoon varmint, and the raccoon got on the bein dummer than what he was from the start.