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: A
Explanation: the principle of friction with swinging and colliding balls.
Answer:
Pressure
Explanation:
The measure of how much force is applied to an object from gas particle bouncing into it is called pressure.
Pressure is defined as the force per unit area on a body.
Mathematically;
Pressure = 
The pressure of a gas is the combined force with which gas molecules bombard a unit area of the wall of the container. It is the sum of all tiny pushes on the wall of the container.
Various units of pressure are atm, mmHg, torr, pascal e.t.c
Answer:
The angle is 18.3 degree.
Explanation:
A uniformly charged infinite plane, density σ = 4 x 10^-9 C/cm^2, is placed vertically in air. A small ball of mass 8 g, with charge q = 10^-8 C, hangs close to the plane, so that the string is initially parallel to the plane. Take g = 9.8m/s2. When in equilibrium, by what angle is the string hanging the ball to the plane?
surface charge density, σ = 4 x 10^-5 C/m^2
Charge, q = 10^-8 C
mass, m = 0.008 kg
Let the angle is A and the tension in the string is T.
The electric field due to a plane is

Now equate the forces,

Answer:
A. 7.1m
B. 3.55m/s
C. 1.775m/s^2
Explanation:
First step is to identify given parameters;
Ball 1: m₁ = 0.5kg, u (initial velocity) =0, t = 2seconds
Ball 2: m₂ = 0.25kg, u = 15m/s, t = 2seconds
<u>Second step:</u> we determine the y-coordinate of ball 1 after 2 seconds, using the equation of motion under gravity as shown below;



Recall, that the ball was thrown from a height of 25m, total y-coordinate of ball 1 after 2 seconds becomes 25m +(-19.6m)
[tex]y_{1} = 5.4m[/tex]
<u>Third step</u>: we determine the y-coordinate of ball 2 after 2 seconds


<u>Fourth step: </u>we determine the y-component of the center mass of the two balls


y = 7.1m
<u>Fifth step:</u> we solve B part of the question; velocity of the center mass of the two balls


velocity = 3.55m/s
<u>Sixth step:</u> we solve C part of the question; acceleration of the center mass of the two balls


acceleration = 1.775 m/s^2