## jewelgurl Will somebody please check my answers??? I will give an award!!! one year ago one year ago

1. jewelgurl

1. The actual mechanical advantage of a machine (1 point) cannot be less than 1. decreases as the input distance increases. increases with greater friction. is less than the ideal mechanical advantage of the machine. (chosen) 2. If you have to apply 40 N of force on a crowbar to lift a rock that weights 400 N, what is the actual mechanical advantage of the crowbar? (1 point) 0.1 10 (chosen) 360 16,000 3. Reducing friction in a machine (1 point) decreases its actual mechanical advantage. decreases the work output. increases its efficiency. increases its ideal mechanical advantage. (chosen) (I'm unsure about the next two) 4. The efficiency of a machine is always less than 100 percent because (1 point) a machine cannot have an IMA (ideal mechanical advantage) greater than 1. some work input is lost to friction. the work input is too small. the work output is too great. 5. A motor with an efficiency of 75 percent must supply 240 J of useful work. What amount of work must be supplied to the motor? (1 point) 75 J 180 J 320 J 420 J

2. ZeHanz

1. OK 2: Not sure, could it be C? 3: OK 4: I'd say B 5. C, because 240J is 75%, so 80J=25% and so 320 J is 100%. Beware though, I'm not an expert in these matters ;)

3. eclipse18

3: C And @ZeHanz, the rest of yours are right.