Answer:
From certain assumptions that the walking speed is 2 m/s, and the stop time is 0.1 s the acceleration would be -20 m/s
Explanation:
Using the average acceleration formula:
where
and
are the changes in the speed and time respectively.
We have by assuming that the walking speed is 2 m/s and the stop time is 0.1s which is equal to the change in time during the stopping.
, where
are the initial speed and final speed respectively, and 
Plugging the previous in the average acceleration formula we get
where the minus sign indicates an acceleration in the opposite direction of the motion (or in other word opposite to the speed's direction).
Answer:
Yes, it's correct
Explanation:
Newton's second Law states that the acceleration of an object is proportional to the net force applied on it, according to the equation:

where
F is the net force on the object
m is the mass of the object
a is the acceleration of the object
We can re-arrange the previous equation in order to solve explicitely for a, the acceleration, and we find:

So, we see that the acceleration is proportional to the net force and inversely proportional to the mass of the object.
Answer:
t = 6.09 seconds
Explanation:
Given that,
Speed, v = 44.1 cm/s
Distance, d = 269 cm
We need to find the time interval of the marble. Speed is distance per unit time.

Hence, the time interval of the marble is 6.09 seconds.
The answer is :78 I think