5 N backwards because it exerts an equal and opposite force
The correct answer to the question is C i.e C represents the friction from air resistance.
EXPLANATION:
Before coming into any conclusion, first we have to understand friction.
The friction is the opposing force which acts tangentially between two bodies in contact when there is a relative motion between them.
The air resistance is that frictional force which is provided by the air to the moving body through it. Hence, the friction from air resistance will be directed opposite to the motion of the body.
In the given diagram, the airplane is going horizontally. The force A acts in forward direction while force C acts in backward direction. The forces B and D are acting vertically. There is no motion in vertical direction. Hence, the net force of A and C will cause the airplane to move.
As the plane is moving along the direction of A, the frictional force must act along the direction of C.
We can do this with the conservation of momentum. The fact it is elastic means no KE is lost so we don't have to worry about the loss due to sound energy etc.
Firstly, let's calculate the momentum of both objects using p=mv:
Object 1:
p = 0.75 x 8.5 = 6.375 kgm/s
Object 2 (we will make this one negative as it is travelling in the opposite direction):
p = 0.65 x -(7.2) = -4.68 kgm/s
Based on this we know that the momentum is going to be in the direction of object one, and will be 6.375-4.68=1.695 kgm/s
Substituting this into p=mv again:
1.695 = (0.75+0.65) x v
Note I assume here the objects stick together, it doesn't specify - it should!
1.695 = 1.4v
v=1.695/1.4 = 1.2 m/s to the right (to 2sf)
Answer:
the internal resistance of the cell is 0.1 ohm.
Explanation:
Given;
p.d at the terminals of a battery at no load, E₁ = 25 V
p.d at the terminals of a battery at a load, E₂ = 24 V
current through the circuit, I = 10 A
The potential drop across the circuit, V = E₁ - E₂
= 25 V - 24 V
= 1 V
The internal resistance of the cell is calculated as follows;
r = V/I
r = 1 / 10
r = 0.1 ohm
Therefore, the internal resistance of the cell is 0.1 ohm.
Answer:
(a) Current is 2831.93 A
(b) 
(c) 
Explanation:
Length of wire l = 3.22 m
Diameter of wire d = 7.32 mm = 0.00732 m
Cross sectional area of wire

Resistance 
Potential difference V = 33.7 volt
(A) current is equal to

(B) Current density is equal to


(c) Resistance is equal to


