<span>Evaporation involves a liquid becoming a gas and sublimation is the change of a solid directly to a gas.Phase changes require either the addition of heat energy (melting, evaporation, and sublimation) or subtraction of heat energy (condensation and freezing.</span>
Instantaneous velocity, on the other hand, describes the motion of a body at one particular moment in time. Acceleration is a vector which shows the direction and magnitude of changes in velocity. Its standard units are meters per second per second, or meters per second squared. (this is for number 3)
Answer:
a
b
Explanation:
From the question we are told that
The mass of the rock is
The length of the small object from the rock is
The length of the small object from the branch
An image representing this lever set-up is shown on the first uploaded image
Here the small object acts as a fulcrum
The force exerted by the weight of the rock is mathematically evaluated as
substituting values
So at equilibrium the sum of the moment about the fulcrum is mathematically represented as
Here is very small so
and
Hence
=>
substituting values
The mechanical advantage is mathematically evaluated as
substituting values
Answer: having to push a rough and heavy box across the floor to move it
Explanation:
The Friction force is any force that is in opposite direction of the motion of an object or fluid due to the contact of this object or fluid with other bodies.
In this sense, there are different types of friction force thath are useful in different situations:
-The <u>Static friction force</u> prevents surfaces from slipping across each other. For example, the friction between your feet and the floor keeping you from slipping.
-The <u>kinetic friction force</u> as the force that helps the tires in a moving vehicle to slow down and stop when necessary.
However, if you want to push a heavy box across the floor to move it, the friction force will not be useful at all.