19) a child on a sled starts from rest at the top of a 15.0° slope. if the trip to the bottom takes 15.2 s,
how long is the slope? assume that frictional forces may be neglected.

288.8 m

Explanation:

We have the following data:

is the time it takes to the child to reach the bottom of the slope

is the initial velocity (the child started from rest)

is the angle of the slope

is the length of the slope

Now, the Force exerted on the sled along the ramp is:

(1)

Where is the mass of the sled and its acceleration

In addition, if we draw a free body diagram of this sled, the force along the ramp will be:

(2)

Where is the acceleration due gravity

Then:

(3)

Finding :

(4)

(5)

(6)

Now, we will use the following kinematic equations to find :

(7)

(8)

Where is the final velocity

Finding from (7):

(9)

(10)

Substituting (10) in (8):

(11)

Finding :

i don't understand is there any other way you can rephrase it plz let me know in the comments and i will do it.

explanation:

air exerts forces on falling objects near earth’s surface.

explanation:

the term 'free falls' refer to object that are falling towards the earth, in a situation in which gravity is the only force acting on the object.

for an object in free fall, the acceleration is constant (g, the gravitational acceleration), and so the velocity of the object constantly increases.

for objects near earth's surface, there is always another force acting on the object: the resistance due to the air. this force is opposed to the direction of fall of the object, and it is proportional to the velocity of the object, so as the object falls down, this force increases up to a point when it balances the force of gravity, and the object continues its motion at constant velocity (called terminal velocity). since in this case gravity is not the only force acting on the object, we are not in a situation of free fall.