B. Kilopascals.
A kilopascal equals to 1,000 pascals; and a pascal is equal to a force of 1 newton per square meter.
Meanwhile,
- a gram and a kilogram are both units of measurement for mass, and
- a newton is a unit of measurement for force.
Answer:
Photoelectric effect
Explanation:
In the photoelectric effect, when an x-ray strikes on a metal surface, the energy is completely absorbed by the metal. If the energy would be equal to or more than work function of metal, electron ejects out. The kinetic energy of the electron which is ejected depends on the energy of the incident radiation and work function of the metal.
Answer:
v = √(10gh/7)
Explanation:
Initial gravitational energy = final rotational energy + kinetic energy
PE = RE + KE
mgh = ½ Iω² + ½ mv²
For a solid sphere, I = ⅖ mr².
For rolling without slipping, ω = v/r.
mgh = ½ (⅖ mr²) (v/r)² + ½ mv²
mgh = ⅕ mv² + ½ mv²
mgh = 7/10 mv²
10/7 gh = v²
v = √(10gh/7)
Answer:
2. The metal surface exerts less frictional force because there are fewer bumps and irregularities on it than there are on the concrete.
Explanation:
Frictional force is a force that is exerted between two surfaces in contact with each other. Frictional force always opposes the direction of relative motion of the two surfaces: for instance, for a ball moving along a surface, the force of friction exerted by the surface on the ball points opposite to the direction of motion of the ball.
The magnitude of the frictional force for a ball moving on a flat surface is given by
where
is the coefficient of friction
m is the mass of the ball
g is the acceleration of gravity
The value of depends on the type of surface involved. In particular, a smooth surface has a smaller value of , while a rough surface will have a bigger value. In this case, we are comparing a smooth metal surface with concrete: since the metal surface has fewer bumps and irregularities than concrete, it has a smaller value of coefficient of friction, so it exerts less frictional force than concrete.
