BR physics chap 1, #37 and 36

[nyr201]

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Hey guys, so this question asks about the magnitude of the acceleration the cart in the experiment experiences as it goes up and down the inclined track.

The explanation to the answer says that the magnitude of acceleration it experiences is related to gravity.

However, in question # 36 for the same experiment it asks what the calculated magnitude of gravity would be for the cart which is 2.5 m/s^2 which isn't gravity obviously.

I'm just confused as to why they're different for both questions. Is it because in #36 its just asking for only one direction? and in 37 it asks for the up and down (complete trip)?

Thanks in advance.

 

[attixx]

The solution for #37 goes on to say that acceleration is some fraction of the acceleration due to gravity (depending on the angle of incline). If it was straight up and down, then yes acceleration would be equal to gravity. But on an incline, a=g(sin&#952😉.

For 36, you are not given an angle of incline so you have to determine acceleration by a=(Vf - Vi)/t. a=(0-5)/2=-2.5 (points opposite the direction of motion).

#37 is just asking how the magnitude of acceleration on the way up compares to the magnitude on the way down. If you could not know they are equal intuitively, then the passage tells you it has a Vi=5m/s, stops at some point, and rolls back down finishing at Vf=5m/s. The acceleration then has to be the same on the way up and back down.