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3 years ago

7

True or false: Balanced forces can change an object's direction?

2 answers:

alex41 [277]3 years ago

7 0

Answer:

False

Explanation:

As per Newton's first law of motion, an object will not change its state of motion until an external unbalanced force is applied on it.

If a balanced force is applied on an object there will be no change in state of motion. Take for example a box. One person moves it to left with force F and another person moves it to the right with same force F. The box will not move. But if the two forces are not equal then a net force will be acting on the box and it will move and its direction will be changed.

slava [35]3 years ago

4 0

The statement is false. Balanced forces can NOT change the speed OR direction of an object's motion. (See Newton's #1 law of motion.)

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True or False. The mass of the pendulum determines the time of a period.

xxTIMURxx [149]

Answer:

False

Explanation:

The time period of a pendulum is given by :

$T=2\pi \sqrt{\dfrac{l}{g}}$

The terms used in the formula are :

l is length of pendulum

g is acceleration due to gravity

It is clear that the formula of time period of a pendulum is independent of its mass. So, the mass of the pendulum is not used to determine the time of a period. Hence, the given statement is false.

8 0

3 years ago

A police car is at rest parallel to the highway and measures the speed of cars. It sends the signal with a frequency of 1200 Hz,

masha68 [24]

Answer:

a) The car was moving at a speed of $29.167\ m.s^{-1}$

b) The negative sign of $v_o$ denotes that the observer is coming towards the police car which is the source of the sound.

c) $f_o=1283.33\ Hz$

Explanation:

Given:

original frequency of the source, $f=1200\ Hz$

speed of the source, $v_s=0\ m.s^{-1}$

velocity of the obstacle car be, $v_o$

speed of sound, $s=350\ m.s^{-1}$

observed frequency, $f_o=1100\ Hz$

<u>Using the equation from the Doppler's effect:</u>

$\frac{f_o}{f} =\frac{(s+v_o)}{(s-v_s)}$

$\frac{1100}{1200} =\frac{(350+v_o)}{350-0}$

$v_o=-29.167\ m.s^{-1}$

a)

The car was moving at a speed of $29.167\ m.s^{-1}$

b)

The negative sign of $v_o$ denotes that the observer is coming towards the police car which is the source of the sound.

c)

Now when, $v_s=50\ m.s^{-1}$

Then, $f_o=?$

Using the Doppler's eq.:

$\frac{f_o}{1200} =\frac{(350+(-29.167))}{(350-50)}$

$f_o=1283.33\ Hz$

3 0

3 years ago

The constant forces F1 = 8 + 29 + 32 N and F2 = 48 - 59 - 22 N act together on a particle during a displacement from the point A

marshall27 [118]

Answer:

-600 J

Explanation:

F₁ = 8i +29 j + 32k

F₂ = 48 i - 59 j - 22 k

F = F₁ +F₂ = 8i +29 j + 32k +48 i - 59 j - 22 k

F = 56i - 30 j + 10 k

displacement d = ( 0 - 20 )i + ( 0 - 15 )j + ( 7 -0) k

d = - 20 i - 15 j + 7 k

Work Done = F dot product d

F . d = - 56 x 20 - 30 x - 15 + 10 x 7

= - 1120 +450 + 70

= -600 J

5 0

3 years ago

A cheetah bites into its prey. One tooth exerts a force of 320 N. The area of the point of the tooth is 0.5 cm². The pressure of

mote1985 [20]

Answer:

<h2>640N/cm^2</h2>

Answer D is correct

Explanation:

$pressure = \frac{force}{area} \\ = \frac{320}{0.5} \\ = 640$

hope this helps

brainliest appreciated

good luck! have a nice day!

6 0

3 years ago

In an attempt to reduce the extraordinarily long travel times for voyaging to distant stars, some people have suggested travelin

Vika [28.1K]

Answer:

Explanation:

Let the required velocity of rocket be v .

We shall use the formula of time dilation to find the velocity of rocket .

t = $\frac{t'}{\sqrt{1-\frac{v^2}{c^2} } }$

t = 430

t' = 38

$430=\frac{38}{\sqrt{1-\frac{v^2}{c^2} } }$

$\sqrt{1-\frac{v^2}{c^2} } }=\frac{38}{430}$

$1-\frac{v^2}{c^2}$ = .0078

$\frac{v^2}{c^2}$ =.9922

$\frac{v}{c}$ = .996

v = .996 x 3 x 10⁸ m /s

= 2.988 x 10⁸ m /s

B )

Kinetic energy of rocket

= 1/2 m v²

= .5 x 20000 x (2.988 x 10⁸ )²

= 8.9 x 10²⁰ J .

C )

This energy is 8.9 times the energy requirement of United states in the year 2005 .

7 0

3 years ago