Answer:
109.66km
Explanation:
Velocity is defined as the change in displacement of a body with respect to time.
Velocity = displacement/Time
Displacement = velocity * time
A truck is traveling due north at 75 km/hr approaching a crossroad and perpendicular road a police car is traveling west toward the intersection at 80 km/hr, then the resultant velocity is gotten using the pythagoras theorem since they are both perpendicular to each other.
v² = 75²+80²
v² = 5625+6400
v² = 12,025
v = √12,025
v = 109.66km/hr
If both vechicles reaches cross road in exactly one hour, the displacement of the truck with respect to the police car = 109.66km/hr * 1 hour
Displacement of the truck with respect to the police car = 109.66km
Explanation:
Given:
Δx = -100
v = 10
a = 20
To find v₀, use a kinematic equation that's independent of time.
v² = v₀² + 2aΔx
(10)² = v₀² + 2(20)(-100)
100 = v₀² − 4000
v₀² = 4100
v₀ = ±64.0
As your teacher said, v₀ can't be +64.0. So v₀ = -64.0.
Next, to find time, use a kinematic equation that's independent of initial velocity.
Δx = vt − ½ at²
-100 = (10) t − ½ (20) t²
-100 = 10 t − 10 t²
-10 = t − t²
t² − t − 10 = 0
Solve with quadratic formula:
t = [ -(-1) ± √((-1)² − 4(1)(-10)) ] / 2(1)
t = (1 ± √41) / 2
t > 0, so:
t = (1 + √41) / 2
t ≈ 3.70
Answer:
The electric current in the wire is 0.8 A
Explanation:
We solve this problem by applying the formula of the magnetic field generated at a distance by a long and straight conductor wire that carries electric current, as follows:

B= Magnetic field due to a straight and long wire that carries current
u= Free space permeability
I= Electrical current passing through the wire
a = Perpendicular distance from the wire to the point where the magnetic field is located
Magnetic Field Calculation
We cleared (I) of the formula (1):
Formula(2)

a =8cm=0.08m

We replace the known information in the formula (2)

I=0.8 A
Answer: The electric current in the wire is 0.8 A