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A rock is tossed straight up from ground level with a speed of 22 m/s. When it returns, it falls into a hole 9.0 m deep. a. What

Vera_Pavlovna [14]

Answer:

(a) $v_{f}=26.08m/s$

(b) $t=4.906seconds$

Explanation:

We will take ground level as origin and upward is positive direction

the givens are

$y_{i}=0\\y_{f}=-9.0m\\ v_{i}=22m/s$

Part (a)

To find the final velocity we use the kinematic equation

So

$(v_{f})^{2} =(v_{i})^{2} +2a(y_{f}-y_{i})\\(v_{f})^{2}=(22m/s)^{2}+2(-9.8m/s^{2} ) (-10-0)\\v_{f}=\sqrt{(22m/s)^{2}+2(-9.8m/s^{2} ) (-10-0)} \\v_{f}=26.08m/s$

Part (b)

To find time of rock trip until it touches the ground we will use simple kinematic equation or simple motion equation

$v_{f}=v_{i}+at\\t=\frac{v_{f}-v_{i}}{a}\\ t=\frac{(-26.08m/s)-(22m/s)}{-9.8m/s^{2} }\\t=4.906seconds$

Notice that we substituted vf with negative sign because its direction is downwards

5 0

3 years ago

A convex lens has a focal length of 16.5 cm. Where on the lens axis should an object be placed in order to get a virtual, enlarg

alexandr402 [8]

Answer:

Object should be placed at a distance, u = 7.8 cm

Given:

focal length of convex lens, F = 16.5 cm

magnification, m = 1.90

Solution:

Magnification of lens, m = - $\frac{v}{u}$

where

u = object distance

v = image distance

Now,

1.90 = $\frac{v}{u}$

v = - 1.90u

To calculate the object distance, u by lens maker formula given by:

$\frac{1}{F} = \frac{1}{u}+ \frac{1}{v}$

$\frac{1}{16.5} = \frac{1}{u}+ \frac{1}{- 1.90u}$

$\frac{1}{16.5} = \frac{1.90 - 1}{1.90u}$

$\frac{1}{16.5} = \frac{ 0.90}{1.90u}$

u = 7.8 cm

Object should be placed at a distance of 7.8 cm on the axis of the lens to get virtual and enlarged image.

6 0

4 years ago

A kettle full of water is brought to a boil in a room with temperature 20Â°c. after 15 minutes the temperature of the water has

kogti [31]

Answer: The temperature after another 5 minutes is 68.5Â°c

Explanation: Please see the attachments below

4 0

3 years ago

How does the abundance of hydrogen and helium support the Big Bang Theory?

Blababa [14]

Answer:

Hydrogen and helium account for nearly all the nuclear matter in today's universe. This is consistent with the standard or "big bang" model. ... Basically , the hydrogen-helium abundance helps us to model the expansion rate of the early universe. If it had been faster, there would be more neutrons and more helium.

Explanation:

Google

3 0

3 years ago

Read 2 more answers

Light travels 186,282 miles in one second. A light year is the distance light travels in one year. It is about 4.3 light years t

deff fn [24]

Answer:

$2.5278035226\times 10^{13}\ miles$