A sled initially at rest slides down a frictionless hill inclined at [tex][tex]$38.0^{\circ}$[/tex][/tex]. It takes 4.24 seconds for the sled to reach the bottom.

What is the final velocity of the sled just before it reaches the bottom of the hill?

[tex]v_f = \, ? \, \text{m/s}[/tex]



Answer :

To determine the final velocity of the sled just before it reaches the bottom of the hill, we will break down the problem into several steps:

1. Given Information:
- The inclined angle of the hill, [tex]\(\theta = 38.0^{\circ}\)[/tex]
- The time taken to reach the bottom of the hill, [tex]\( t = 4.24 \, \text{s} \)[/tex]
- The acceleration due to gravity, [tex]\( g = 9.81 \, \text{m/s}^2 \)[/tex]

2. Convert the angle from degrees to radians:
To use trigonometric functions, we need the angle in radians.
[tex]\[ \theta \text{ (in radians)} = 0.6632251157578453 \][/tex]

3. Calculate the acceleration along the incline:
The effective acceleration [tex]\( a \)[/tex] down the incline can be calculated using the component of gravitational acceleration along the slope, which is given by [tex]\( g \sin(\theta) \)[/tex].
[tex]\[ a = 6.039639072944708 \, \text{m/s}^2 \][/tex]

4. Determine the initial velocity:
Since the sled starts from rest, the initial velocity [tex]\( u \)[/tex] is:
[tex]\[ u = 0 \, \text{m/s} \][/tex]

5. Use the kinematic equation to find the final velocity:
We use the equation [tex]\( v = u + at \)[/tex] where:
- [tex]\( v \)[/tex] is the final velocity.
- [tex]\( u \)[/tex] is the initial velocity, which is [tex]\( 0 \, \text{m/s} \)[/tex].
- [tex]\( a \)[/tex] is the acceleration along the incline.
- [tex]\( t \)[/tex] is the time taken.

Plugging in the known values:
[tex]\[ v = 0 + 6.039639072944708 \, \text{m/s}^2 \times 4.24 \, \text{s} \][/tex]
[tex]\[ v = 25.608069669285566 \, \text{m/s} \][/tex]

So, the final velocity of the sled just before it reaches the bottom of the hill is:
[tex]\[ v_f = 25.608069669285566 \, \text{m/s} \][/tex]