Answer:
Explanation:
When a camera shifts focus from a faraway object to a nearby object, the lens-to-film distance must increase. Likewise, when it shifts focus from a nearby object to a distant object, there must be an increase in the lens to film distance (that is, the image distance).
Therefore, if the picture of an object that is far away, the lens must move towards the film.
The focal length cannot be changed because it is fixed for a lens. Nevertheless, in order to focus on an object, the image distance can be changed.
the object distance of both lenses are positive.
Answer:
The magnitude of the flux of electric field through a square of surface area is zero.
Explanation:

It is given that square box is parallel to yz-plane which has normal vector perpendicular to plane in x-direction. Angle between normal vector of area and electric field is 90°. Substituting in (1)

Answer:
1.05 J.
Explanation:
Kinetic Energy: This is the energy possessed by a body due to its motion. The S.I unit of kinetic energy is Joules (J). The formula of kinetic energy is given as
Ek = 1/2mv²................. Equation 1
Where Ek = kinetic energy, m = mass of the uniform rod, v = liner velocity of the rod.
But,
v = αr .......................... Equation 2
Where α = angular velocity of the rod, r = radius of the circle.
Given: α = 3.6 red/s, r = 120/2 = 60 cm = 0.6 m.
Substitute into equation 2
v = 3.6(0.6)
v = 2.16 m/s.
Also given: m = 450 g = 0.45 kg.
Substitute into equation 1
Ek = 1/2(0.45)(2.16²)
Ek = 1.05 J.
Answer: The softer barrier is the better option
Explanation:
1) When is a car is moving at a certain speed, it has a certain amount of momentum (p=mv). A collision against a barrier would cause its momentum to decrease to 0. A change in momentum is Impulse
2) The formula for Impulse: J = f * Δt
J is Impulse
f is the force applied during the time Δt
A tough barrier would produce a smaller Δt, which means more force is applied on the car. (J is always constant)
A softer barrier would apply less force on the car, which means Δt is large.
Answer: The softer barrier is the better option