As shown in Figure 3,the internal resistance of the battery r=1.5Ω,R1=R2=R3=4Ω,R4=10Ω (a)When the key S1 and S2 are disconnected, the voltage meter read 4V, find the power emf.
(b)When the key S1 and S2 are closed,
(i)What is the reading of the voltmeter?
(ii)What is the reading of the ammeter?

Identify the forces that contribute to the centripetal force on the object in each of the following examples: a. a bicyclist moving around a flat, circular track b. a bicycle moving around a flat, circular track c. a racecar turning a corner on a steeply banked curve

Laboratory experiments, observational field studies, and model-building are all examples of different forms of scientific investigations.  in what way do laboratory experiments primarily differ from other forms of scientific investigations?   a.  a laboratory experiment is the only accepted form of investigation within the scientific community.  b.  studies about how things behave in nature or studies involving very large objects are best answered through laboratory experiments.  c.  laboratory experiments involve the identification and control of variables.  d.  data can only be generated through laboratory experiments, not other forms of investigation.

Which situation will produce the greatest change of momentum