Physics questions?

Question

Why does the size of a projectile not make a difference in the air resistance, velocity, and distance?

At what height will a projectile take 1.0s to fall?

At what angle will a projectile thrown from level ground to the same level ground go the furthest?

Answer 1

1) It's not the size of the projectile, but the aerodynamics of the item. For example, I can take a 1-kg cube shape and toss it so far, or I can reshape that 1-kg item into a conical cylinder (aka bullet) and shoot it much further.

2) 9.8m (gravity acceleration on Earth is 9.8m/s^2)

3) In a vacuum and the right acceleration, 45 degrees (velocity up equals velocity down)

Answer 2

When calculating projectile motion in physics books the air resistance is considered negligible and the affect of the mass or weight is not considered because they assume the system is in a vaccum. This makes for easier calculations.

In real life air resistance does make a difference and so does weight but that is calculations for higher math. These factors are used in ballistics.

In vertical motion all things fall at the same rate, the rate of gravity. In most systems it is simple to use meters. and gravity is 9.8 m/s^2.
so for an object to fall 1 sec y=1/2 g(t^2) = 1/2 (9.8) ( 1^2) = 4.9 meters.

When discussing projectile motion the path of the object is broken down into two forces. The vertical and the horizontal.
The distance the projectile travels is called the range. To find the Range = Vo^2 ( sin 2 (theta) ) / Gravity.
Theta being 45 degrees and 2(theta ) = 90 degrees and sin of 90 = 1 therefore the farthest distance is at 45 degrees. Any other angle will give you a sin smaller than 1. Example: theta 43 degrees (sin2(43) ) = .997 and theta 47 degrees(sine 2(47) ) = .997

Answer 3

> Why does the size of a projectile not make a difference in the air resistance, velocity, and distance?

This is not true: The projectile's size absolutely DOES make a difference in the air resistance (and hence also affects the velocity and distance). For example, suppose you have two perfect spheres made of lead: one is 1 inch in diameter, and the other is 10 inches in diameter. At any given speed, the air resistance on the 10-inch sphere will be about 100 times as great as the air resistance on the 1-inch sphere.

If your teacher doubts this, have him/her look up some formulas for air resistance (for example, here: http://en.wikipedia.org/wiki/Drag_(physics)). He/she will find that all the formulas include "d" or "r" (the diameter or radius of the object). Size does make a difference!

> At what height will a projectile take 1.0s to fall?

about 16 feet (4.9 meters). (This is ignoring air friction.) Use this formula:

h = gt²/2
(g = 32.2 ft/sec²; or 9.81 m/sec²)

Answer 4

The size of a projectile does make a difference when it comes to air resistance especially if if it has a wide surface facing the direction of motion.

An object that is sixteen feet above the Earth's surface will take one second to hit.

45 degrees

Answer 5

The size and path of projectile do change in air resistance.But most of the questions in text books tell us to neglect the effects of air resistance.It is because students haven't reached the level to solve questions with the effect of air resistance.

To get the height we need to use the equation
s=ut+1/2at^2
,where s is the height
u is initial velocity when projectile is going to fall
t is the time
So,s=0+1/2(10)(1)^2
=5m

At angle 45.
Range of projectile is given by
R=v^2xsin2@/g

So in order to get maximum range,sin2@ must be 1.Solve it trigonometrically and you wil get the answer 45 degrees.

Answer 6

Question 1: I don't know

Question 2: I don't know too

Question 3: 45 degrees. Believe me, I tried. By the way, you're pretty...