A force of 77 N is used to move a desk 1.5 m. How much work was done?

Justin Bieber is thrown horizontally at 10.0 m/s from the top of a cliff 122.5 m high.

sveticcg [70]

===> Distance fallen from rest in free fall =

   (1/2) (acceleration) (time²)

   (122.5 m) = (1/2) (9.8 m/s²) (time²)

Divide each side by (4.9 m/s²): (122.5 m / 4.9 m/s²) = time²

   (122.5/4.9) s² = time²

Take the square root of each side: 5.0 seconds

===> (Accelerating at 9.8 m/s², he will be dropping at
   (9.8 m/s²) x (5.0 s) = 49 m/s
when he goes 'splat'. We'll need this number for the last part.)

===> With no air resistance, the horizontal component of velocity
doesn't change.

Horizontal distance = (10 m/s) x (5.0 s) = 50 meters .

===> Impact velocity = (10 m/s horizontally) + (49 m/s vertically)

   = √(10² + 49²) = 50.01 m/s arctan(10/49)

   =    50.01 m/s at 11.5° from straight down,
      away from the base of the cliff.

7 0

3 years ago

Read 2 more answers

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

while looking at a graph, you notice a period of time where the line is perfectly horizontal what is most likely taking place du

aev [14]

Answer:

where the y axis is

Explanation:

In more simple terms, a horizontal line on any chart is where the y-axis values are equal. If it has been drawn to show a series of highs in the data, a data point moving above the horizontal line would indicate a rise in the y-axis value over recent values in the data sample.

7 0

3 years ago

What could contribute to an inaccurate vital sign reading?

amid [387]

<span>Lack of training in getting the vital sign or worst, not knowing the right way to take the vital sign could contribute to an inaccurate vital sign reading. For example, if you are tasked to get the respiration of the patient, the rule is to count inhale and exhale as one. But if you were not able to know this rule, and you counted inhale as one and exhale as another, this could impair the vital reading. </span>

7 0

4 years ago

!!HELP HELP!!

borishaifa [10]

Answer:

7.5s

Explanation:

Given parameters:

Velocity = 30m/s

Deceleration = 4m/s²

Unknown:

Time it takes for the car to come to complete rest = ?

Solution:

To solve this problem, we use the kinematics expression below:

v = u + at

Since this is a deceleration

v = u - at

v is the final velocity

u is the initial velocity

a is the acceleration

t is the time taken

v - u = -at

0 - 30 = -4 x t

-30 = -4t

t = 7.5s

6 0

3 years ago