Answer:
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.
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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.
