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3 years ago

13

Shannon is playing tennis. She swings her racket to hit the tennis ball and sends the ball flying in the same direction.

1 answer:

Gnoma [55]3 years ago

3 0

Answer:

she used force to swing her ball all way back

Explanation:

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The barrel of a rifle has a length of 0.855 m. A bullet leaves the muzzle of a rifle with a speed of 553 m/s. What is the accele

Novay_Z [31]

Answer:

Acceleration of the bullet will be 1778835.6 $m/sec^2$

Explanation:

We have given length of the barrel refile s= 0.855 m

When the bullet leaves the muzzle its velocity is 553 m/sec

So final velocity v = 553 m/sec

Initial velocity will be 0 that is u = 0 m/sec

According to third equation of motion $v^2=u^2+2as$

$553^2=0^2+2\times a\times 0.855$

$a=178835.6m/sec^2$

5 0

3 years ago

A sky diver with a mass of 70kg jumps from an aircraft. The aerodynamic drag force acting on the sky diver is known to be Fd=kV^

xeze [42]

Answer:

$v_{max}=52.38\frac{m}{s}$

$v_{100}=33.81$

Explanation:

the maximum speed is reached when the drag force and the weight are at equilibrium, therefore:

$\sum{F}=0=F_d-W$

$F_d=W$

$kv_{max}^2=m*g$

$v_{max}=\sqrt{\frac{m*g}{k}} =\sqrt{\frac{70*9.8}{0.25}}=52.38\frac{m}{s}$

To calculate the velocity after 100 meters, we can no longer assume equilibrium, therefore:

$\sum{F}=ma=W-F_d$

$ma=W-F_d$

$ma=mg-kv_{100}^2$

$a=g-\frac{kv_{100}^2}{m}$ (1)

consider the next equation of motion:

$a = \frac{(v_{x}-v_0)^2}{2x}$

If assuming initial velocity=0:

$a = \frac{v_{100}^2}{2x}$ (2)

joining (1) and (2):

$\frac{v_{100}^2}{2x}=g-\frac{kv_{100}^2}{m}$

$\frac{v_{100}^2}{2x}+\frac{kv_{100}^2}{m}=g$

$v_{100}^2(\frac{1}{2x}+\frac{k}{m})=g$

$v_{100}^2=\frac{g}{(\frac{1}{2x}+\frac{k}{m})}$

$v_{100}=\sqrt{\frac{g}{(\frac{1}{2x}+\frac{k}{m})}}$ (3)

$v_{100}=\sqrt{\frac{9.8}{(\frac{1}{2*100}+\frac{0.25}{70})}}$

$v_{100}=\sqrt{\frac{9.8}{(\frac{1}{200}+\frac{1}{280})}}$

$v_{100}=\sqrt{\frac{9.8}{(\frac{3}{350})}}$

$v_{100}=\sqrt{1,143.3}$

$v_{100}=33.81$

To plot velocity as a function of distance, just plot equation (3).

To plot velocity as a function of time, you have to consider the next equation of motion:

$v = v_0 +at$

as stated before, the initial velocity is 0:

$v =at$ (4)

joining (1) and (4) and reducing you will get:

$\frac{kt}{m}v^2+v-gt=0$

solving for v:

$v=\frac{ \sqrt{1+\frac{4gk}{m}t^2}-1}{\frac{2kt}{m} }$

Plots:

5 0

3 years ago

Waves can carry either ____ or __________ energy?

Oksanka [162]

Mechanical or Electromagnetic

3 0

2 years ago

Read 2 more answers

How far will 20 N of force stretch a spring with a spring constant of 140 N/m?

densk [106]

Answer:

0.143 m

Explanation:

The relationship between force applied on a string and stretching of the spring is given by Hooke's law:

$F=kx$

where

F is the force exerted on the spring

k is the spring constant of the spring

x is the stretching of the spring from its equilibrium position

In this problem, we have:

F = 20 N is the force applied on the spring

k = 140 N/m is the spring constant

Solving for x, we find how far the spring will stretch:

$x=\frac{F}{k}=\frac{20}{140}=0.143 m$

7 0

2 years ago

Which of the following is not accurate when describing solids? A. Solids are better conductors of heat than liquids B. The amoun

Elza [17]

B. The amount of pressure exerted by a solid is solely dependent on its mass
i just took the test

3 0

3 years ago

Read 2 more answers