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soldier1979 [14.2K]
3 years ago
10

You are watching an archery tournament when you start wondering how fast an arrow is shot from the bow. Remembering your physics

, you ask one of the archers to shoot an arrow parallel to the ground. You find the arrow stuck in the ground 68.0 m away, making a 3.00o angle with the ground. How fast was the arrow shot?
Physics
1 answer:
olga nikolaevna [1]3 years ago
6 0

Answer:112.82 m/s

Explanation:

Given

range of arrow=68 m

Angle=3^{\circ}

as the arrow travels it acquire a vertical velocity v_y

v_y=u+at

v_y=0+9.81\times t-------1

Range is given by

R=ut

where u=initial velocity

68=u\times t

t=\frac{68}{u}

substitute the value of t in eqn 1

v_y=9.81\times \frac{68}{u}

v_y\times u=9.81\times 68=667.08--------2

and tan(3)=\frac{v_y}{u}

v_y=utan(3)=0.0524u

substitute it in 2

0.0524 u^2=667.08

u^2=12,728.644

u=112.82 m/s

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An input for of 80 N is used to lift an object weighing 240 N with a system of pulleys. How far must the rope around the pulleys
sammy [17]

Answer:

4.2 m

Explanation:

Note: If energy is conserved, i.e no work is done against friction

Work input = work output.

Work output = Force output × distance,

Work input = force input × distance moved moved.

Therefore,

input force×distance moved = output force × distance moved........................Equation 1

Given: input force = 80 N, output force = 240 N, output distance = 1.4 m

Let input distance = d

Substitute into equation 1

80×d = 240×1.4

80d = 336

d = 336/80

d = 4.2 m.

Thus the rope around the pulley must be pulled 4.2 m

7 0
3 years ago
To test the performance of its tires, a car
velikii [3]

<u>Answer</u>:

The coefficient of  static friction between the tires and the road is 1.987

<u>Explanation</u>:

<u>Given</u>:

Radius of the track, r =  516 m

Tangential Acceleration a_r=  3.89 m/s^2

Speed,v =  32.8 m/s

<u>To Find:</u>

The coefficient of  static friction between the tires and the road = ?

<u>Solution</u>:

The radial Acceleration is given by,

a_{R = \frac{v^2}{r}

a_{R = \frac{(32.8)^2}{516}

a_{R = \frac{(1075.84)}{516}

a_{R = 2.085 m/s^2

Now the total acceleration is

\text{ total acceleration} = \sqrt{\text{(tangential acceleration)}^2 +{\text{(Radial acceleration)}^2

=>= \sqrt{ (a_r)^2+(a_R)^2}

=>\sqrt{ (3.89 )^2+( 2.085)^2}

=>\sqrt{ (15.1321)+(4.347)^2}

=>19.4791 m/s^2

The frictional force on the car will be f = ma------------(1)

And the force due to gravity is W = mg--------------------(2)

Now the coefficient of  static friction is

\mu =\frac{f}{W}

From (1) and (2)

\mu =\frac{ma}{mg}

\mu =\frac{a}{g}

Substituting the values, we get

\mu =\frac{19.4791}{9.8}

\mu =1.987

8 0
3 years ago
What is it that lives if it is fed, and dies if you give it a drink?
Anna71 [15]

Fire is it that lives if it is fed, and dies if you give it a drink.

<h3><u>Explanation:</u></h3>

Fire is very essential part of human life. It is used for cooking food and for other important activities. Without fire we cannot not survive. Something or the other should be heated before consumption and this can be achieved only with fir. It is also used in the darker places for viewing many things around us.

Thus, fire can survive if we give fuel or any wooden pieces and when water is poured on it it will turn off. Hence Fire is the one that survives when it is fed and dies when water is given as a drink to it.

4 0
3 years ago
Need help asap pls
Zinaida [17]
B. third

for every action there is a reaction*
6 0
1 year ago
5. How much time does it take for a bird flying at a speed of 45 kilometers per hour to travel a
Lyrx [107]

Answer:

40h

Explanation:

Use the velocity formula to solve

v = \frac{d}{t}

In this question, you are given velocity v = 45km/h, and you are given a distance, d = 1800km.  Time in this question is what you'll need to find.

Start by rearranging the velocity formula, to isolate for t.

v = \frac{d}{t}

Start by multiplying both sides by t

v(t) = \frac{d}{t}(t)\\\\vt = d

Then divide both sides by v.

vt\frac{1}{v} = d/v\\ \\t = \frac{d}{v}

Now that you've isolated for time, sub in your values and calculate.

t = \frac{d}{v} = \frac{1800km}{45km/h} = 40 h

8 0
2 years ago
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