Answer:
C. The car from driving off the road on a curve
Explanation:
A centripetal force actually causes circular motion. This occurs when an object moves in a circular path or a circle,a force will definitely act on it.
For instance, a car travelling in a circular path must definitely experience this force acting on it, even when the car moves at a constant speed. If it does not exist the object will definitely spin off in a direction tangential to the circular path or curve.
Kinetic energy is calculated as such: 
| therefore, 
Answer:
Explanation:
Given
length of window 
time Frame for which rock can be seen is 
Suppose h is height above which rock is dropped
Time taken to cover 
so using equation of motion
where y=displacement
u=initial velocity
a=acceleration
t=time
time taken to travel h is
Subtract 1 and 2 we get
and from equation 
so 
and 
so 
substitute the value of 
in equation 2
Answer:
Charge on each is 2 x 10⁻¹⁰.
Explanation:
We know that Force between two point charges is given b the Coulomb's law as:
F = kq₁q₂/r^2
k = 9 x 10^9
r = 3.00 cm
= 0.03 m
q₁ = q₂
F = 4.00 x 10^-7
Rearranging the formula, we get:
F = k q²/r²
q² = Fr²/k
q² = 4 x 10⁻⁷ x 0.03²/(9x10⁹)
q² = 4 x 10⁻²⁰
q = 2 x 10⁻¹⁰
As there is force of repulsion between the charges, the charges must be both positive or both negative.
