Answer:

Explanation:
From this exercise, our knowable variables are <u>hight and initial velocity </u>


To find how much time does the <u>ball strike the ground</u>, we need to know that the final position of the ball is y=0ft


Solving for t using quadratic formula


or 
<u><em>Since time can't be negative the answer is t=6.96s</em></u>
1. In the first 1.5 seconds, the lift accelerates from 0 to 3m/s. By definition, the acceleration is the ratio between the change in velocity and the time elapsed to change the velocity.
The change in velocity is
.
The time elapsed is 1.5 seconds, so the acceleration is
meters per second squared.
2. We know, from the previous point, that the lift travelled 20m from the first floor. Since it returns to the first floor after the ascent, it must travel again those same 20m, just in reverse (descending instead of ascending). So, the total distance travelled is
meters.
The displacement, though, is zero, because it measures the distance between the starting and ending point of a certain motion. Since the lift starts and ends its motion at the same place (the first floor), its total displacement is zero.
Answer:
Part a)
When there is no friction then acceleration is

Part b)
if there is friction force along the inclined then acceleration is

Explanation:
Part a)
As we know that the skier is on inclined plane
So here if there is no friction then net force along the inclined plane is given as

now acceleration of the skier is given as




Part b)
if there is friction force along the inclined then net force along the inclined plane is given as

now acceleration of the skier is given as




The charge going to the clothes iron needs to be grounded so the iron does not make any shock
Answer:
The moist air mass would be denser
Explanation:
Density is defined as mass per unit volume. Hence the density of a substance (solid, liquid or gas) is directly proportional to its mass and inversely proportional to the volume occupied.
The mass of a gas is the product of its number of moles and its molar mass (mass = number of moles × molar mass), which indicates that the mass is directly proportional to molar mass, so the higher the molar mass, the higher the mass of different gases at equal volumes, temperature and pressure.
From the information given, the molar weight of dry air = 29g/mole.
The molar weight of moist air = molar weight of dry air + molar weight of water vapour = 29 + 18 = 47g/mole.
Therefore since higher molar mass transits to higher mass, it can be said that moist air of molar mass 47g/mole is denser than dry air of molar mass 29g/mole at equal volume, temperature and pressure.
Simple picture the two gasses in two transparent jars, the heavier gas (moist air) settles more at the bottom of the jar, and has less random motion hence is more compressed and denser, than dry air that has more freedom to move randomly because of its lesser weight.