-- The acceleration due to gravity is 32.2 ft/sec² . That means that the
speed of a falling object increases by an additional 32.2 ft/sec every second.
-- If dropped from "rest" (zero initial speed), then after falling for 4 seconds,
the object's speed is (4.0) x (32.2) = <em>128.8 ft/sec</em>.
-- 128.8 ft/sec = <em>87.8 miles per hour</em>
Now we can switch over to the metric system, where the acceleration
due to gravity is typically rounded to 9.8 meters/sec² .
-- Distance = (1/2) x (acceleration) x (time)²
D = (1/2) (9.8) x (4)² =<em> 78.4 meters</em>
-- At 32 floors per 100 meters, 78.4 meters = dropped from the <em>25th floor</em>.
The 5 points are certainly appreciated, but I do wish they were Celsius points.
Answer:
A physical change is a change to the physical—as opposed to chemical—properties of a substance. They are usually reversible. The physical properties of a substance include such characteristics as shape (volume and size), color, texture, flexibility, density, and mass.
Answer:
19.01 N
Explanation:
F = Force being applied to the crate = 45 N
= Angle at which the force is being applied = 
Horizontal component of force is given by

The horizontal component of the force acting on the crate is 19.01 N.
Answer:
Explanation:
Let the ball is thrown upwards with speed u and reaches upto height h.
Use III equation of motion

here, final velocity v = 0
So, 
Now as the ball reaches the maximum height, it starts falling freely. Let it strkes with the ground with velocity v'.

here, u = 0
So, 
It means the velocity is same as the velocity of projection.