I find that the context often makes the problem harder. I could reframe question 18 as follows. I don't think this would improve the rate at which students solve it.
You look up some specifications for your little Smart Car and find that it has a mass of 800 kg with you inside. From the specifications you also determine that when you step on the gas the engine supplies 2000 N of force to the car. Find the acceleration you would feel under those conditions. Bonus part - how does that compare to the acceleration you would experience in free fall?
I fail to see how a Smart Car would engage their interest. 
For that matter an approximately ¼ gee acceleration would be somewhat pathetic even for a Smart Car. (As an aside, I think it would be more useful to define the standard gee as 10m/s² rather than as 9.80665 m/s². Easier to use and anyone who needs a more precise figure than 10m/s² probably needs to use the local gravity rather than the genericized standard gravity.)
But more seriously, would anyone in the "real world" ever make a calculation like that? My point was not simply that we ought to provide a context, but provide a context that motivates students. Most word problems fail seriously on the motivation point and an unmotivating context may well be worse than no context at all.
Are you mad? 9.8 m/s² is what it is!
