The average velocity = Displacement between two points/ Time taken for that displacement
In this case An ion's position vector is initially r = 8.0 i - 4.0 j + 3.0 k, and 8.0 s later it is r = 4.0 i + 8.0 j - 6.0 k
So, displacement = 4.0 i + 8.0 j - 6.0 k - (8.0 i - 4.0 j + 3.0 k)
= -4.0 i + 12.0 j - 9.0 k
So velocity, V = (-4.0 i + 12.0 j - 9.0 k)/8
= -0.5 i + 1.5 j - 1.125 k
So average velocity during 8 seconds = -0.5 i + 1.5 j - 1.125 k
Answer:
Normal force=mg
Explanation:
The reaction force of weight is the normal force.
in order to find the normal for we need to write all the forces and set it equal to the net force:
N-mg=ma (since it is a constant speed the a=0)
N=mg
Answer:
Current needed = 704A
Explanation:
Using the fomula; torque(τ) = (I)(A)(B)Sinθ
Where B = uniform magnetic field
I = current and A = Area
Diameter = 19cm = 0.19m so, radius = 0.19/2 = 0.095m
Area(A) = πr^(2) = πr^(2)
= π(0.095)^(2) = 0.0284 m^(2)
Now, B(earth)= 5x10^-5 T
While, we can ignore the angle because it's insignificant since the angle of the wire is oriented for maximum torque in the earth's field.
Now, if we arrange the formula to solve for charge (I):
I = (τ)/(A)(B)
I = (1.0x10^-3) / (0.0284)(5x10^-5)
I = 704A
We know the equation of motion v = u+ at, where v is the final velocity, u is the initial velocity, a is the acceleration and t is the time taken.
In this case Final velocity before collision = 115 km/hr = 115*5/18 = 31.94 m/s
Time taken by car to reach this velocity = 8.83 seconds
Initial velocity = 0 m/s
v = u +at
31.94 = 0 + a*8.83
a = 3.62 
So acceleration of car just before collision = 3.62
