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emmasim [6.3K]
3 years ago
12

Two cars leave towns 480 kilometers apart at the same time and travel toward each other. One car's rate is 20 kilometers per hou

r less than the other's. If they meet in 3 hours, what is the rate of the slower car

Physics
1 answer:
dlinn [17]3 years ago
8 0

Answer:

70 km/h

Explanation:

Let the velocity of car A is v km/h, thus the velocity of car B is (v - 20) km/h.

They meet after 3 hours.

Distance traveled by car A in 3 hours = v x 3 = 3 v

Distance traveled by car B in 3 hours = (v - 20) x 3 = 3v - 60

Total distance traveled is 480 km

So, 3 v + 3 v - 60 = 480

6 v - 60 = 480

6 v = 540

v = 90 km/h

Thus, the speed of car A is 90 km/h and the speed of car B is 90 - 20 = 70 km/h.

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g You drop a 3.6-kg ball from a height of 3.5 m above one end of a uniform bar that pivots at its center. The bar has mass 9.9 k
Salsk061 [2.6K]

Answer:

h = 3.5 m

Explanation:

First, we will calculate the final speed of the ball when it collides with a seesaw. Using the third equation of motion:

2gh = v_f^2 - v_i^2\\

where,

g = acceleration due to gravity = 9.81 m/s²

h = height = 3.5 m

vf = final speed = ?

vi = initial speed = 0 m/s

Therefore,

(2)(9.81\ m/s^2)(3.5\ m) = v_f^2 - (0\ m/s)^2\\v_f = \sqrt{68.67\ m^2/s^2}\\v_f = 8.3\ m/s

Now, we will apply the law of conservation of momentum:

m_1v_1 = m_2v_2

where,

m₁ = mass of colliding ball = 3.6 kg

m₂ = mass of ball on the other end = 3.6 kg

v₁ = vf = final velocity of ball while collision = 8.3 m/s

v₂ = vi = initial velocity of other end ball = ?

Therefore,

(3.6\ kg)(8.3\ m/s)=(3.6\ kg)(v_i)\\v_i = 8.3\ m/s

Now, we again use the third equation of motion for the upward motion of the ball:

2gh = v_f^2 - v_i^2\\

where,

g = acceleration due to gravity = -9.81 m/s² (negative for upward motion)

h = height = ?

vf = final speed = 0 m/s

vi = initial speed = 8.3 m/s

Therefore,

(2)(9.81\ m/s^2)h = (0\ m/s)^2-(8.3\ m/s)^2\\

<u>h = 3.5 m</u>

6 0
3 years ago
Someone help me, I'm stuck
Bas_tet [7]
C is the answer hope that helps you
3 0
3 years ago
The amplitude of a simple harmonic oscillator will be doubled by:a) doubling only the initial speedb) doubling the initial displ
OLEGan [10]

Answer:

When both initial speed and initial displacement is doubled then amplitude will be doubled.

Explanation:

Given that :- Amplitude of simple harmonic Oscillator  is doubled.

So,

     Formula of Simple harmonic oscillator is  X=A\sin\ (2\pi ft +\phi)  ...........(1)

                                                            Where X = Position in (m,cm,km.....)

                                                                        A = Amplitude  in (m,cm,km.....)

                                                                        F = Frequency in (Hz)

                                                                        T = Time in (sec.)

                                                                        Ф = Phase in (rad)

  For initial displacement taking t=0 we get,

                          Initial displacement = A\sin(\phi)    .................(2)            

Now taking equation (1) and differentiating it w.r.t to (t) we get

                                \frac{dx}{dt} = 2\pi fA\cos\ (2\pi ft+\phi)

                                 V= 2\pi fA\cos\ (2\pi ft+\phi)

taking t=0 for initial speed then we get,

                                Initial speed = 2\pi fA\cos\phi    ...............(3)

observing equation (2) & (3) that the initial displacement and initial speed depends on the Amplitude of the Oscillator.

Hence,

when both initial speed and displacement is doubled then amplitude will be doubled.

4 0
4 years ago
Sunitha can type 1800 words in half an hour. What is her typing speed in words per minute?
Andre45 [30]

Answer:

60words/minute

Explanation:

If Sunitha can type 1800 words in half an hour, this can be expressed as;

1800 words = 30 minutes

To get her typing speed per minute, we will use the formula

Speed = Number of words/Time used

Typing speed = 1800/30

Typing speed = 60words/minute

Hence her typing speed in words per minute is 60words/minute

6 0
3 years ago
how to A golf ball of mass 0.045 kg is hit off the tee at a speed of 45 m/s. The golf club was in contact with the ball for 3.5
Alexandra [31]

Answer: a) 12857.1 m/s/s b) 578.6 N

Explanation:

Impulse = change in momentum

Ft = mV2 - mV1

V = AT, 45 / .0035 = 12857.1 m/s/s

(b) .045 x 12857.1 = 578.6 N

4 0
3 years ago
Read 2 more answers
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