Which of the following are sources of mechanical energy?

If an astronaut takes an object to the moon the following is true (choose only one). a the mass will change but the weight will be the same. b both the mass and the weight of the object will be the same. c the weight will change but the mass will be the same. d both the mass and the weight of the object will change.

You are in a car that is traveling along highway 99 at a constant speed of 16 m/s. suddenly you see a truck also traveling at a constant speed (3.0 m/s) that is on a track to cross your lane from an alley on the right and is moving into your lane (which you can’t get out of, because of broader safety concerns like head on traffic in the other lane). your car’s maximum acceleration is 6.0 m/s2 (either way, gettingfaster or slower) and your reaction time of 0.75 s between first seeing the truck and applying the brake or the accelerator. the distance from the side street, where you first notice the truck, to the right edge of your lane is 2.0 m and the lane also has a fixed width of 4.0m, check for yourself that all these numbers are reasonable. you will assume a reasonable size for your car. the truck is 3.0 m wide.a) how long will it take the truck from the moment you notice it, to block enough of your lane so you can’t slip past while also staying in your own lane (in seconds)? b) how far will your car travel (in meters) while your brain is figuring out what to do? c) if you decide that braking is in your best interests how long will it take you to come to a complete stop once you begin the process of braking (in s)? d) what is the minimum distance (in m) you must be from the truck to successfully stop before hitting

Amajor impediment to wide acceptance of electric vehicles even on the part of people who use their cars almost exclusively for commuting is the inability to use their electric vehicles for occasional extended trips. in an attempt to make purchasing electric vehicles more attractive to commuters, one electric vehicle producer is planning to offer customers three days free rental of a conventional car for every 1,000 miles that they drive their electric vehicle. which of the following, if true, most threatens the plan's prospects for success? (a) many electric vehicles that are used for commercial purposes are not needed for extended trips. (b) because a majority of commuters drive at least 100 miles a week, the cost to the producer of making good the offer would add considerably to the already high price of electric vehicles. (c) the relatively long time it takes to recharge the battery of an electric vehicle can easily be fitted into the regular patterns of car use characteristic of commuters. (d) although electric vehicles are essentially emission-free in actual use, generating the electricity necessary for charging an electric vehicle's battery can burden the environment. (e) some family vehicles are used primarily not for commuting but for making short local trips, such as to do errands.