Answer:
(b) B
Explanation:
The direction of force on a current carrying wire in a magnetic field can be found using the right hand rule, which states that-"stretch the thumb in the direction of the current, and point the fingers in the direction of magnetic field. The direction of palm will then give the direction of force on the wire
On wire B the forces due to A and C act in the same direction and so strengthen each other. they get added up because the forces act in the same direction.
on wires A and C the forces (due to B and C and A and B
respectively) act in opposite directions and therefore tend to cancel out.
Explanation:
Given that,
The slope of the ramp, 
Mass of the box, m = 60 kg
(a) Distance covered by the truck up the slope, d = 300 m
Initially the truck moves with a constant velocity. We know that the net work done on the box is equal to 0 as per work energy theorem as :

u and v are the initial and the final velocity of the truck
(b) The work done on the box by the force of gravity is given by :

Here, 


W = -24550.13 J
(c) What is the work done on the box by the normal force is equal to 0 as the angle between the force and the displacement is 90 degrees.
(d) The work done by friction is given by :


Hence, this is the required solution.
Answer:
4939200 m
Explanation:
v = Velocity of sound in air = 343 m/s (general value)
For the echo to reach Rip van Winkle it must cover the distance to the mountain twice. So, time taken for the sound traveling to the mountain once

Distance is given by

The distance to the mountain is 4939200 m
Answer:
Potassium
k = Potassium
Potassium Has 19 Electrons
the atomic mass is 39.0983
Answer:
Explanation:
Total tension must support the weight of the child and provide the necessary centripetal force.
2T = m(g + v²/R)
2(414) = 35.0(9.81 + v²/3.02)
828 = 35.0(9.81 + v²/3.02)
23.65 = 9.81 + v²/3.02
13.847 = v²/3.02
41.81 = v²
v = 6.47 m/s
F = 2(414) = 828 N (ignoring the weight of the chains and seat)