A sample is brought to the laboratory and it is determined that one-eighth of the original

on a high way a car is driven 80 km the first 1 he of travel, 50km during the next 0.5 he, and 40 km in the final 0.5 hr. What i

Leno4ka [110]

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

Total distance = (80 + 50 + 40) = 170 km

Total time = (1 + 0.5 + 0.5) = 2 hours

Average speed = (170 km) / (2 hrs) = 85 km/hr .

4 0

3 years ago

A police car is stopped at a red light facing west. When the light turned green, a sports car speeds past it heading west at wit

frutty [35]

Answer:

14 seconds

Explanation:

Distance covered by sports car is measured with 21*t where t is time.

Distance covered by police is measured with at^2/2(t-time, a-acceleration) as it doesnt have starting velocity. If the distances are equal(police catches sport car)

then we have 21t=3/2*t^2 Solving this equation we get t=14 & t=0;

excluding the starting point we have 14 seconds

3 0

3 years ago

Read 2 more answers

A music fan at a swimming pool is listening to a radio on a diving platform. The radio is playing a constant- frequency tone whe

joja [24]

Answer:

The Doppler Effect is given by the following relation;

$f' = \left (\dfrac{v + v_0}{v - v_s} \right) \times f$

Where;

f' = The frequency the observer hears

f = Actual frequency of the wave

v = The velocity of the sound wave

$v_o$ = The velocity of the observer

$v_s$ = The velocity of the source

Where the observer is stationary, we have;

(i) When the source is moving in the direction of the observer

$f' = \left (\dfrac{v }{v - v_s} \right) \times f$

(ii) When the source is receding from the observer, we have;

$f' = \left (\dfrac{v }{v + v_s} \right) \times f$

Therefore;

(a) A person left behind on the platform

For a person left behind on the platform, we have that the radio source is receding, therefore, we have;

$f' = \left (\dfrac{v }{v + v_s} \right) \times f$

(1) Given that (v + $v_s$ ) > v, therefore, v < (v + $v_s$ ), f' < f, the frequency heard by the person left on the platform, f', is smaller (lower) than the frequency produced by the radio

(2) The frequency is not constant as the speed of the source is increasing while it under the acceleration due to gravity

(3) During the fall, the speed of the source continuously increases under the effect of gravitational attraction and therefore the frequency heard by the person on the platform becomes progressively smaller

(b) A person down below floating on a rubber raft

For the the person down below on the rubber raft, the radio source is advancing

Therefore, the radio source is moving towards the person at rest down on the rubber raft, therefore, we have;

$f' = \left (\dfrac{v }{v - v_s} \right) \times f$

(1) Given that (v - $v_s$ ) < v, therefore, f' > f, the frequency heard by the person down below floating on the rubber raft, f', is greater (higher) than the frequency produced by the radio

(2) The frequency is not constant as the speed of the source is increasing while it under the acceleration due to gravity

(3) During the fall, the speed of the source continuously increases under the effect of gravitational attraction and therefore the frequency heard by the person on the platform becomes progressively greater (higher)

Explanation:

7 0

3 years ago

When a physical change in a sample occurs what does not change

Lelu [443]

Answer:

When a physical change in a sample occurs, composition of the sample does not change. It stays the same. It stays the same. Also, the properties of the sample will still be the same

5 0

3 years ago

What is Plancks constant (h)?

Tatiana [17]

Planck's constant is 4.39048042 × 10-67 m4 kg2 / s2.

6 0

3 years ago