A snowboarder traveling at 9 meters per second snowboards to a stop at the top of a ramp in 4 seconds. What is the skateboarder’s acceleration? *

Acceleration = -9/4 meter per second square

Explanation:

This problem can be solved using first equation of motion which is

v = u + at           where

v is final velocity

u is initial velocity

a is the constant rate of acceleration

t is the time of motion of body

note: this law is applicable only when acceleration is constant.

Given

initial velocity (u) = 9m/sec

It is given that body stops at top of ramp.

when any body is not moving its velocity is 0.

As body stops and is not moving hence its velocity is 0.

it is also the final velocity

thus,

final velocity (v) = 0

t = 4 second

we have to get a

using the equation of motion, and substituting the value as given above we have

v = u + at  

0 = 9 + a*4

0 = 9 + 4a

=> 4a = -9

=>  a = -9/4

Thus, acceleration is -9/4 meter per second square.

negative sign implies that acceleration is opposite of the direction of velocity.

This, it also intuitive as body speed is decreasing, it can be understood that direction of acceleration is opposite to that of velocity

Acceleration in improper fraction .

acceleration in mixed fraction form = -(2  1/4) meter per second square.