Answer:
A
Explanation:
1. When the block moves across a table top, F(pulling) = - F(frictional).
Sum of this forces = 0, so the block moves with uniform speed.
2. When the block is pulled on top of the table covered with beads
F(pulling) > - F(frictional).
So, the sum of forces (∑F) is a number that is more than 0 and directed to the direction of movement.
So, a = ∑F / m is positive and constant. Speed is increasing because
v(t) = v(0)+at
a is constant and directed forward.
That means a is acceleration, and constant.
One of the most common energy transformations is the transformation between potential energy and kinetic energy. In waterfalls such as Niagara Falls, potential energy is transformed to kinetic energy. The water at the top of the falls has gravitational potential energy. As the water plunges, its velocity increases. Thanks to google!!!! LOL :)
The heat released or absorbed by a process where temperature changes is calculated from the product of the mass of the sample, its heat capacity (4.18 J/g C for water) and the change of the temperature.
Heat = mC(T)
Heat = 90 (4.8) (64) = 27648 J or 27.65 kJ needed
