All categories

4 years ago

How much power should a braked 1.5t car have to be braked to reduce its speed from 30m / s to 10m / s in 5s?

Physics

1 answer:

grandymaker [24]4 years ago

7 0

Answer:

-120000 W

Explanation:

Power = change in energy / time

P = ΔE / t

P = (½ mv₂² − ½ mv₁²) / t

P = m (v₂² − v₁²) / (2t)

Given m = 1.5 t = 1500 kg, v₂ = 10 m/s, v₁ = 30 m/s, and t = 5 s:

P = (1500 kg) ((10 m/s)² − (30 m/s)²) / (2 × 5 s)

P = -120000 W

You might be interested in

An astronaut in a satellite 1600km above the Earth experience a gravitational force magnitude 700N on earth.The Earth's radius i

Brilliant_brown [7]

Answer:

The magnitude of the gravitational force which the astronaut experience in satellite $= 448$ Newton

Explanation:

As we know

Gravitational force F = $\frac{GMm}{r^2}$

Where G is the gravitational constant $6.67 * 10^{-11}$

M is the mass of earth $= 6* 10^{24}$

m is not given

r is the radius of earth $6 400*10^3$

Substituting the given values, we get -

$F = \frac{6.67*10^{−11}*6*10^{24}* m}{(6400*10^3)^2}$

$m = 71.6$ Kg

Gravitational force in the satellite

$F = \frac{6.67*10^{−11}*6*10^{24}* m}{(6400*10^3 + 1600 *10^3)^2}\\F = 448$ N

3 0

3 years ago

Two ice skaters, Lilly and John, face each other while at rest, and then push against each other's hands. The mass of John is tw

seropon [69]

Answer:

Lilly's speed is two times John's speed.

Explanation:

m = Mass

a = Acceleration

t = Time taken

u = Initial velocity

v = Final velocity

The force they apply on each other will be equal

$F=ma\\\Rightarrow a_l=\frac{F}{m_l}$

$F=ma\\\Rightarrow a_j=\frac{F}{2m_l}\\\Rightarrow a_j=\frac{1}{2}a_l$

$v=u+at\\\Rightarrow v_l=0+\frac{F}{m_l}\times t\\\Rightarrow v_l=a_lt$

$v=u+at\\\Rightarrow v_l=0+\frac{F}{2m_l}\times t\\\Rightarrow v_j=\frac{1}{2}a_lt\\\Rightarrow v_j=\frac{1}{2}v_l\\\Rightarrow v_l=2v_j$

Hence, Lilly's speed is two times John's speed.

4 0

3 years ago

10. A car starts from rest at a stop light and reaches 20 m/s in 3.5

liq [111]

B i believe not really sure but that math i did seems about right

3 0

4 years ago

Read 2 more answers

You hear a sound with a frequency of 256 Hz. The amplitude of the sound increases and decreases periodically: It takes 2 seconds

Fiesta28 [93]

These 255.75 Hz and 256.25 Hz sounds can be thought of as a sum of two waves with frequencies.

Answer: Option A

<u>Explanation:</u>

To solve this, it is necessary to take into account the concepts related to frequency and period, and how they are related to each other.

Let frequency of beat = f

The relationship that defines both agreements is given by the equation,

$f=\frac{1}{T}$

Then the frequency for the previous period given (2sec) is

$f=\frac{1}{2}=0.5$

The beat frequency of two frequencies is equal to the difference between the two frequencies, then

$f=\left|f_{1}-f_{2}\right|$

$f=|255.75-256.25|=0.5 H z$

Hence, Option A is correct.

Similarly we can check like these for other options too as below,

For option B, $f=|255.5-256.5|=1 Hz$ .

For Option C, $f=|255-257|=2 H z$

For Option D, $f=|254-258|=4 H z$

For Option E, $f=|256-2|=254 H z$

Therefore, the sum of the frequencies in the sound wave would be 256.25Hz and 255.75Hz.

8 0

3 years ago

An unknown element is found to have two naturally occurring isotopes, 200X and 210X with atomic masses of 200.028 and 210.039 re

Kruka [31]

Answer:

The average atomic mass of X is 206.0346

Explanation:

Atomic mass of 200X = 200.028

% abundance of 200X = 40% = 40/100 = 0.4

Atomic mass of 210X = 210.039

% abundance of 210X = 100% - 40% = 60% = 60/100 = 0.6

Average atomic mass of X = (0.4×200.028) + (0.6×210.039) = 80.0112 + 126.0234 = 206.0346

5 0

4 years ago

How much power should a braked 1.5t car have to be braked to reduce its speed from 30m / s to 10m / s in 5s?​

How much power should a braked 1.5t car have to be braked to reduce its speed from 30m / s to 10m / s in 5s?