Tools we'll use:
-- Gravitational potential energy = (mass) x (gravity) x (height)
-- Kinetic energy (of a moving object) = (1/2) (mass) x (speed)²
When the pendulum is at the top of its swing,
its potential energy is
(mass) x (gravity) x (height)
= (5 kg) x (9.8 m/s²) x (0.36 m)
= (5 x 9.8 x 0.36) joules
= 17.64 joules .
Energy is conserved ... it doesn't appear or disappear ...
so that number is exactly the kinetic energy the pendulum
has at the bottom of the swing, only now, it's kinetic energy:
17.64 joules = (1/2) x (mass) x (speed)²
17.64 joules = (1/2) x (5 kg) x (speed)²
Divide each side by 2.5 kg:
17.64 joules / 2.5 kg = speed²
Write out the units of joules:
17.64 kg-m²/s² / 2.5 kg = speed²
(17.64 / 2.5) (m²/s²) = speed²
7.056 m²/s² = speed²
Take the square root
of each side: Speed = √(7.056 m²/s²)
= 2.656 m/s .
Looking through the choices, we're overjoyed to see
that one if them is ' 2.7 m/s '. Surely that's IT !
_______________________________
Note:
The question asked for the pendulum's 'velocity', but our (my) calculation
only yielded the speed.
In order to describe a velocity, the direction of the motion must be known,
and the question doesn't give any information on exactly how the pendulum
is hanging, and how it's swinging.
We know that at the bottom of its swing, the motion is completely horizontal,
but we have no clue as to what direction. So all we can discuss is its speed.
Answer:d
Explanation:
Given
Initially, the ice cube is floating over the water
When the cube is pressed to touch the bottom, it is submerged fully
Therefore more buoyant force is acting on it
At first, a part of the volume is submerged in the water, so the buoyant force is less, but as the entire cube is immersed in the water, the buoyant force increases.
wavelength =wavevelocity
--——————
Frequency
Frequency = 1/T => 1 / 6.73 = 0.1486
Wave velocity = L/T => 3.75 / 6.73 = 0.5572
Therefore, wave length = 0.5572/0.1486 = 3.75m
Die meisten von ihnen haben die Möglichkeit zu den Anderen zu kommen oder die Möglichkeit für die Zeit der Arbeit mit dem Auto und der Wohnung zu
