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Lena [83]
4 years ago
13

help me.. a car moves for half of its time at 80km/h nd for rest of time at 40km/h.total distance coverd is 60km..wat is averge

speed of car?
Physics
1 answer:
nalin [4]4 years ago
5 0
Let's use ' t ' to represent half of the time, in hours.

The distance traveled in the first half of the time is  (80 t) km.

The distance traveled in the last half of the time is  (40 t) km.

The total distance covered is    (80t + 40t) = (120t)  km.

You said that the total distance covered was  60 km,
so ...
                             120 t  =  60 km

Divide each side by  120 :      t (half of the time) = 0.5 hour

Average speed = (total distance covered) / (time to cover the distance)

                           =      (60 km)  /  (1 hour)

                           =            60 km/hr .
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Answer:

1.17 m

Explanation:

From the question,

s₁ = vt₁/2................ Equation 1

Where s₁ = distance of the reflecting object for the first echo, v = speed of the sound in air, t₁ = time to dectect the first echo.

Given: v = 343 m/s, t = 0.0115 s

Substitute into equation 1

s₁ = (343×0.0115)/2

s₁ = 1.97 m.

Similarly,

s₂ = vt₂/2.................. Equation 2

Where s₂ = distance of the reflecting object for the second echo, t₂ = Time taken to detect the second echo

Given: v = 343 m/s, t₂ = 0.0183 s

Substitute into equation 2

s₂ = (343×0.0183)/2

s₂ = 3.14 m

The distance moved by the reflecting object from s₁ to s₂ = s₂-s₁

s₂-s₁ =  (3.14-1.97) m = 1.17 m

7 0
3 years ago
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In classical physics, consider a 2 kg block hanging on a spring with a spring constant of 50 N/m. Ignore air resistance. The blo
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Answer:

v = 0

Explanation:

This problem can be solved by taking into account:

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- The equation for the velocity of a simple harmonic motion

x = \frac{2\pi }{T}Asin(\frac{2\pi }{T}t)   ( 2 )

where m is the mass of the block, k is the spring constant, A is the amplitude (in this case A = 14 cm) and v is the velocity of the block

Hence

T = \sqrt{\frac{2 kg}{50 N/m}} = 0.2 s

and by reeplacing it in ( 2 ):

v = \frac{2\pi }{0.2s}(14cm)sin(\frac{2\pi }{0.2s}(0.9s)) = 140\pi  sin(9\pi ) = 0

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