6. If a car went a distance of 225 kilometers in 4

A rock falls from a vertical cliff that is 4.0 m tall and experiences no significant air resistance as it falls. At what speed w

Zinaida [17]

Answer:

v = 6.3 m/s

Explanation:

Since no significant air resistance exists, total mechanical energy must be kept constant at any time.
At the top of the cliff, all the energy is gravitational potential energy, as follows:

$E_{i} = K_{i} + U_{i} = 0 + U_{i} (1)$

If we choose the ground level as our zero reference level for the gravitational potential energy, Ui is simply:
Ui = m*g*h (1)
At any height, the sum of the kinetic and the gravitational potential energy must be equal to (1).
We know from the question, that at the point of interest, both types of energies must be equal each other, so we can write the following expression from (1):

$m*g* h = 2*\frac{1}{2}*m*v^{2} (2)$

Dividing both sides by m, simplifying, and solving for v, we get:

$v = \sqrt{g*h} =\sqrt{9.8m/s2*4.0m} = 6.26 m/s (3)$

v = 6.3 m/s (with two significative figures)

8 0

3 years ago

The largest and the smallest balls used in the experiment are with diameter 9.52 mm, and 2.38 mm respectively. For a glycerin wi

svlad2 [7]

Answer

given,

largest diameter of balls = 9.52 mm = 0.00476 m

radius = 0.00476

smallest diameter of ball = 2.38 mm = 0.00238 m

radius = 0.00119

viscosity = 1.5 Pa.s

density of the ball = 1.42 g/cm

$F = 6\pi \eta r V_t$

$F = \dfrac{mv}{t}$

$F = \dfrac{\dfrac{4}{3}\pi\ r^3\times (\rho-\sigma) \times 0.99 V_T}{t}$

$6\pi \eta r V_t = \dfrac{\dfrac{4}{3}\pi\ r^3\times rho \times 0.99 V_T}{t}$

$t = \dfrac{\dfrac{4}{3}\pi\ r^3\times rho \times 0.99 V_T}{6\pi \eta r V_t}$

$t= \dfrac{0.22 r^2 (\rho-\sigma) }{\eta}$

for small balls

$t= \dfrac{0.22\times 0.00119^2 (1460-1300)}{1.5}$

t = 0.033 ms

for larger ball

$t= \dfrac{0.22\times 0.00476^2 (1460-1300)}{1.5}$

t = 0.531 ms

6 0

4 years ago

A uniform piece of sheet steel is shaped as in the figure below. (Both axes are marked in increments of 2). Compute the x and y

Elena-2011 [213]

"increments of 8" means the major divisions are 0,8,16,24 ?

x axis, calculate the moment arms from 0 
3x4, 2x12, 1x20 
from an arbitrary C 
3(c-4) + 2(c-12) + (c-20) = 0 
3c - 12 + 2c -24 + c - 20 = 0 
6c = 56 
c = 9.33 

y axis 
3x3, 1x12, 2x20 
3(c-4) + 1(c-12) +2 (c-20) = 0 
3c - 12 + c - 12 + 2c - 40 = 0 
6c = 64 
c = 10.67 

so center is x = 9.33, y = 10.67

5 0

3 years ago

Read 2 more answers

Suppose the microphone on an AM radio is not working properly. Which best explains how this will affect the

Otrada [13]

Answer: Sound waves will not be transformed into electrical signals.

Explanation: Just took the test and got a 100!

6 0

3 years ago

Read 2 more answers

Parallel rays from a distant object are traveling in air and then are incident on the concave end of a glass rod with a radius o

skad [1K]