Consider a circuit. there are three resistors, r1, r2, and r; and two emf’s, e1 and e2. the directions of the currents are indicated. applying kirchhoff’s rules, what equations
does the loop badcb yield?
1.e1−e2−i1r2−i2r1=0
2. e1 − e2 − i2 r2 − i1 r1 = 0
3. e1 + e2 + i2 r2 − i1 r1 = 0
4.e1−e2−i1r2+i2r1=0
5. e1 + e2 + i2 r2 + i1 r1 = 0
6. e1 + e2 − i2 r2 + i1 r1 = 0
7. e1 − e2 + i2 r2 + i1 r1 = 0
8.e1+e2−i2r2−i1r1=0
9.e1−e2−i2r2+i1r1=0
10.e1−e2+i2r2−i1r1=0

Imagine you are riding on a yacht in the ocean and traveling at 20 mph. you then hit a golf ball at 100 mph from the deck of the yacht. you see the ball move away from you at 100mph, while a person standing on a near by beach would observe your golf ball traveling at 120 mph (20 mph + 100 mph). now imagine you are aboard the hermes spacecraft traveling at 0.1c (1/10 the speed of light) past mars and shine a laser from the front of the ship. you would see the light traveling at c (the speed of light) away from your ship. according to einstein’s special relativity, how fast will a person on mars observe the light to be traveling? a) 0.1c (1/10 the speed of light) b) c (the speed of light) c)1.1c (c+0.1c)

Two carts, one of mass 2m and one of mass m, approach each other with the same speed, v. when the carts collide, they hook together. assume that positive momentum is to the right. which graph best represents the momentum of both carts over time, before and after the collision?

The voltage applied across a given parallel-plate capacitor is doubled. how is the energy stored in the capacitor affected?