Answer:B,C,D
Explanation:
Thermodynamic efficiency is given by

efficiency can be increased by Keeping
constant and increasing 
Keeping
constant and decreasing
by increasing 
by decreasing
ratio
W=mg
m = W/g = 390N/ 9.8 m/s^2 = 39.8 kg
some people round g to 10 m/s^2 and this will give answer of 39 kg, which is wrong
Answer:
A) False
B) False
C) True
D) False
Explanation:
A) False, because when leaving the field, the coil experiences a magnetic force to the right.
B) When the loop is entering the field, the magnetic flux through it will increase. Thus, induced magnetic field will try to decrease the magnetic flux i.e. the induced magnetic field will be opposite to the applied magnetic field. The applied magnetic field is into the plane of figure and thus the induced magnetic field is out of the plane of figure. Due to that reason, the current would be counterclockwise. So the statement is false.
C) When the loop is leaving the field, the magnetic flux through the loop will decrease. Thus, induced magnetic field will try to increase the magnetic flux i.e. the inducued magnetic field will be in the same direction as the applied magnetic field. The applied magnetic field is into the plane of figure and thus the induced magnetic field is also into the plane of figure. Due to that reason, the current would be clockwise. So the statement is true.
D) False because when entering the field magnetic force will be toward left side
2) b) The height above the surface of the earth
3) b) air pressure differences that make air rise or sink
4) a) TC (I'm not sure about this)
5) I don't know this one. Sorry :(
6) a) true
7) a) true
8) b) false (I'm not sure about this)
Sorry I couldn't answer all your questions, but I hope this helps!
Momentum is a product of mass and the velocity of a body. The initial momentum is always equal to the final momentum during collisions between two bodies.
Therefore; M1U1 +M2U2 = M1V1+ M2V2, where m1 is the mass of tracey and m2 is the mass of jonas, while u is the initial velocity and v is the final velocity.
(32 ×0)+ (45×0) = (32 × v1) + (45 × 0.50)
0 = 32V1 + 22.5
32 V1 = -22.5
V1 = - 0.703 ( negative indicates difference in direction)
There, Tracey's speed will be 0.703 m/s