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4 years ago

A football was kicked so that it traveled 65 yards in 3.0 total seconds. What was the speed

Physics

1 answer:

Olin [163]4 years ago

4 0

Answer:

vx = 65 yd/3 sec = 21.7 yd/sec since horizontal speed is constant

vy = g t = (32 / 3) yd/sec^2 * 1.5 sec = 16 yd/sec where 32/3 is the acceleration due to gravity in yds / sec^2 and 1.5 is the time to travel each way in the vertical direction

V = (vx^2 + vy^2)^1/2 = (21.7^2 + 16^2)^1/2 = 27 yd/sec

tan theta = vy/vx = 16 / 21.7 = .737 theta = 36.4 deg

You can check using the range formula:

R = v^2 sin (2 theta) / g = 27^2 * .955 / (32 / 3) = 65.3 yds

The difference from 65 yds may be rounding error.

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1. An 80-kg quarterback jumps straight up in the air right before throwing a 0.43-kg football horizontally at 15 m/s. How fast w

algol13

Answer:

1) 0.0806 m/s

2) External forces don't act on the system during the jump

Explanation:

velocity of ball ( Vbf )= 15 m/s

mass of quarter back ( Mq )= 80 kg

mass of football ( Mb ) = 0.43 kg

A) How fast will be be moving backward just after releasing the ball

we can determine this speed with the use of conservation of momentum equation

= Mb ( Vbf - Vbi ) = Mq ( Vq )

where Vq = Mb ( Vbf - Vbi ) / Mq

= 0.43 ( 15 m/s - 0 ) / 80 kg

= 0.0806 m/s

B) External forces don't act on the system during the jump

4 0

3 years ago

A sumo wrestler is 330 pounds. How much force does the earth exert in him? Define Mass Define Weight

Oksana_A [137]

Answer:

a large matters of body with no shape is mass

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3 years ago

What does physics have to do with science and chemistery

Rainbow [258]

Physics is known as the fundamentals of science, as all the branches of science, whether it is biology, chemistry, ecology, botany, environmental science, geology, geography, and more all follow the laws of physics, such as laws of thermodynamics, etc. Chemistry is existent because of physics due to the Conservation of mass. Once you get to a much deeper level of science, you will notice that all the fields of science start to blend together and all add up to one huge painting!

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3 years ago

Which two forces are always equal and opposite for an object on a surface?

Kisachek [45]

Answer:

Suppose any object with mass in our planet.

The object will be affected by the gravitational force, that pulls the object down. Now, a table in your dining room is also affected by this force, but the table is in a surface (the ground) and it does not move.

We know that if an object does not move, then the net force acting on it is equal to zero, this means that there is a force equal and opposite ot the gravitational force.

This force is the normal force, that the ground applies on the table. This force comes as a "response" to the table pushing the ground (By 3rd Newton's law).

So two forces that are always equal and opposite are the forces caused by this law.

5 0

3 years ago

Aconstant current of 3 Afor 4 hours is required to charge an automotive battery. If the terminal voltage is V, where t is in hou

kirza4 [7]

Answer:

(a) 43.2 kC

(b) 0.012V kWh

(c) 0.108V cents

Explanation:

<u>Given:</u>

i = current flow = 3 A
t = time interval for which the current flow = $4\ h = 4\times 3600\ s = 14400\ s$
V = terminal voltage of the battery
R = rate of energy = 9 cents/kWh

<u>Assume:</u>

Q = charge transported as a result of charging
E = energy expended
C = cost of charging

Part (a):

We know that the charge flow rate is the electric current flow through a wire.

$\therefore i = \dfrac{Q}{t}\\\Rightarrow Q =it\\\Rightarrow Q = 3\times 14400\\\Rightarrow Q = 43200\ C\\\Rightarrow Q = 43.200\ kC\\$

Hence, 43.2 kC of charge is transported as a result of charging.

Part (b):

We know the electrical energy dissipated due to current flow across a voltage drop for a time interval is given by:

$E = Vit\\\Rightarrow E = V\times 3\times 4\\\Rightarrow E = 12V\ Wh\\\Rightarrow E = 0.012V\ kWh\\$

Hence, 0.012V kWh is expended in charging the battery.

Part (c):

We know that the energy cost is equal to the product of energy expended and the rate of energy.

$\therefore \textrm{Cost}=\textrm{Energy}\times \textrm{Rate}\\\Rightarrow C = ER\\\Rightarrow C = 0.012V\times 9\\\Rightarrow C =0.108V\ cents$

Hence, 0.108V cents is the charging cost of the battery.

4 0

4 years ago