Answer:
75 m /s
Explanation:
Acceleration of ball a = change in velocity / time
=( 90 - 60)/ 3 = 10 m s⁻²
Initial velocity u = 60 m/s
a = 10 m s⁻²
time t = 3
distance traveled s = ut + 1/2 at²
= 60 x 3 + .5 x 10 x 3 x 3
= 225 m
Average velocity = total distance traveled /time
= 225 / 3 = 75 m/s
Answer:
Second, fundamental unit of time, now defined in terms of the radiation frequency at which atoms of the element cesium change from one state to another. The second was formerly defined as 1/86,400 of the mean solar day—i.e., the average period of rotation of the Earth on its axis relative to the Sun.
source britannica
Explanation:
Answer:
i) kinetic friction; ii) The friction force always acts in the opposite direction to the movement of the surface where friction exists.
Explanation:
Part i )
At that time the type of friction that exists is kinetic, as there is movement by the wheel. At the moment when the wheel remains in rest over the inclined plane, the friction force which would be used will be the static force.
Part ii)
The friction force always acts in the opposite direction to the movement of the surface where friction exists. It is not opposed to the sense of movement. In order for the wheel to rise on the inclined plane, it must turn to the right, that is to say in the clockwise direction, therefore the friction force must go in the opposite direction to the rotation of the wheel, that is to say, go in the opposite direction to the movement of the surface under friction effect, that is why it points in the same direction of displacement of the wheel.
Health and safety are two reasons
The marbles that are 'more energetic' fall out of the tray, in the same way particles have enough energy to escape and turn into a gas.