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3 years ago

8

Hakeem throws a 11.5 g ball straight down from a height of 2.0 m. the ball strikes the floor at a speed of 7.8 m/s. what was the

initial speed of the ball? assume that air resistance is negligible.

1 answer:

Sonja [21]3 years ago

7 0

11.4 m/s G + H - m/s X 2

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Calculate the magnitude of the focal length and power of a spherical mirror that has a radius of 5.00 cm.

yarga [219]

Answer:

2.5 cm

40 D

Explanation:

When the radius of curvature of a lens is divided by 2 we get the focal length of the lens.

Focal length is given by

$f=\dfrac{R}{2}\\\Rightarrow f=\dfrac{5}{2}\\\Rightarrow f=2.5\ cm$

The focal length of the lens is 2.5 cm

When we divide 1 by the focal length in the unit of meters we get the power of a lens

Power of a lens is given by

$P=\dfrac{1}{f}\\\Rightarrow P=\dfrac{1}{0.025}\\\Rightarrow P=40\ D$

The power of the lens is 40 D

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4 years ago

Is it safe to drive your 1600-kg car at speed 34 m/s around a level highway curve of radius 190 m if the effective coefficient o

adoni [48]

Answer:

It is unsafe

Explanation:

v = Velocity of car = 34 m/s

r = Radius of turn = 190 m

$\mu$ = Coefficient of static friction = 0.5

m = Mass of car = 1600 kg

g = Acceleration due to gravity = 9.81 m/s²

The centripetal force is given by

$F_c=m\frac{v^2}{r}\\\Rightarrow F_c=1600\frac{34^2}{190}\\\Rightarrow F_c=9734.73\ N$

The frictional force is given by

$F_f=\mu mg\\\Rightarrow F_f=0.5\times 1600\times 9.81\\\Rightarrow F_f=7848\ N$

If the centripetal force is greater than the frictional force then the car will slip which makes it unsafe.

Here, the centripetal force is greater than the frictional force which makes it unsafe to drive it at that speed.

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3 years ago

A person who is good at caring for others might enjoy a career as a

julia-pushkina [17]

He or she would enjoying doing a job as a caretaker

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4 years ago

An engine is designed to obtain energy from the temperature gradient of the ocean. What is the thermodynamic efficiency of such

rewona [7]

Answer:

0.035 (3.5 %)

Explanation:

The thermodynamic efficiency is given by:

$\eta = 1 - \frac{T_C}{T_H}$

where

$T_C$ is the cold temperature

$T_H$ is the hot temperature

In this problem we have

$T_C = 5 ^{\circ}C+ 273 = 278 KT_H = 15^{\circ}C+273 = 288 K$

So the efficiency is

$\eta = 1 - \frac{278 K}{288 K}=0.035$

6 0

3 years ago

How much electrical energy is used by the river cooker oven rated 800 W ,230 V is switched on for 30 minutes

mariarad [96]

Answer:

E = 1440 kJ

Explanation:

It is given that,

Power of a cooker oven is 800 W

Voltage at which it is operated is 230 V

Time, t = 30 minutes = 1800 seconds

We need to find the electrical energy used by the cooker oven. The product of power and time is equal to the energy consumed. So,

$E=P\times t\\\\E=800\ W\times 1800\ s\\\\E=1440000\ J\\\\\text{or}\\\\E=1440\ kJ$

So, electrical energy of 1440 kJ is consumed by the cooker oven.

8 0

3 years ago