If a car has a velocity of 85 km/hr, how long will it take to accelerate to 45 km/hr if the acceleration is -3 km/hr/sec?

A 30-m-long rocket train car is traveling from Los Angeles to New York at 0.5c when a light at the center of the car flashes. Wh

Novosadov [1.4K]

Given that,

Distance =30 m

speed = 0.5c

(A). We need to find the bell and siren simultaneous events for a passenger seated in the car

According to given data

The distance travelled by the light to reach either side of the rocket train car is same.

So, The two events are simultaneous and the bell and siren are the simultaneous events for a passenger seated in the car.

(B). We need to calculate time interval between the events

Using formula of time dilation

$\Delta t=\dfrac{\Delta t'}{\sqrt{1-\dfrac{v^2}{c^2}}}$ .....(I)

Where, $\delta t'$ = proper time

$\delta t$ = time interval between the events

The time interval between the events measured in a reference frame

The proper time in this case is

$\Delta t'=\Delta t_{1}-\dfrac{v\Delta x}{c^2}$

For the second interval,

Put the value of $\Delta t'$ in the equation (I)

$\Delta t_{2}=\dfrac{\Delta t_{1}-\dfrac{v\Delta x}{c^2}}{\sqrt{1-\dfrac{v^2}{c^2}}}$

Put the value in the equation

$\Delta t_{2} = \dfrac{0-\dfrac{0.5c\times30}{c^2}}{\sqrt{1-\dfrac{0.5^2c^2}{c^2}}}$

$\Delta t_{2}=\dfrac{-15}{3\times10^{8}\sqrt{1-0.25}}$

$\Delta t_{2}=-5.77\times10^{8}\ s$

Negative sign shows the siren rings before the bell ring.

Hence, (A). Yes, the bell and siren are simultaneous events.

(B). The siren sounds before the bell rings.

8 0

2 years ago

If you are driving 128.4 km/h along a straight road and you look down for 3.0s, how far do you travel during this inattentive pe

ser-zykov [4K]

Answer:

107 m

Explanation:

Convert km/h to m/s:

128.4 km/h × (1000 m / km) × (1 h / 3600 s) = 35.67 m/s

Distance = rate × time

d = 35.67 m/s × 3.0 s

d = 107 m

8 0

3 years ago

Find the angle of prism if the ray just fail to emerge from 2nd face When ray of light falls normallly on the face of prism of R

Usimov [2.4K]

The angle of prism is 41.81 degrees.

<u>Explanation:</u>

For no emergence to be taken place, inside a prism, Total Internal Reflection (TIR) should take place at the second surface. For TIR, at second surface, angle of refraction must be greater than critical angle. Angle of prism is related to refraction as,

$A>r_{1}+C$