Answer:
the answer is A.) -1 * 10^3[N]
Explanation:
The solution consists of two steps, the first step is using the following kinematic equation:
![v=v_{i} +a*t\\where:\\v=final velocity [m/s]\\v_{i}=initial velocity [m/s]\\a=acceleration[m/^2]\\t=time[s]\\](https://tex.z-dn.net/?f=v%3Dv_%7Bi%7D%20%2Ba%2At%5C%5Cwhere%3A%5C%5Cv%3Dfinal%20velocity%20%5Bm%2Fs%5D%5C%5Cv_%7Bi%7D%3Dinitial%20velocity%20%5Bm%2Fs%5D%5C%5Ca%3Dacceleration%5Bm%2F%5E2%5D%5C%5Ct%3Dtime%5Bs%5D%5C%5C)
The initial velocity is 10 [m/s], and the final velocity is zero because the car stops in 0.5[s].
Replacing:
![0=10+a*(0.5)\\a=-20[m/s^2]](https://tex.z-dn.net/?f=0%3D10%2Ba%2A%280.5%29%5C%5Ca%3D-20%5Bm%2Fs%5E2%5D)
Now in the second part, we need to use the second law of Newton, this law relates the forces with the acceleration of a body.
In the moment when the car stops suddenly the driver will feel the force of the seatbelt acting in the opposite direction of the movement.
![F=m*a\\F=50[kg]*(-20[m/s^2])\\units\[kg]*[m/s^2]=[N]\\F=-1000[N] or -1*10^{3} [N]](https://tex.z-dn.net/?f=F%3Dm%2Aa%5C%5CF%3D50%5Bkg%5D%2A%28-20%5Bm%2Fs%5E2%5D%29%5C%5Cunits%5C%5Bkg%5D%2A%5Bm%2Fs%5E2%5D%3D%5BN%5D%5C%5CF%3D-1000%5BN%5D%20or%20-1%2A10%5E%7B3%7D%20%5BN%5D)
The minus sign means that the force is acting in the opposite direction of the movement.
Answer:
we need to imagines as albert enstein said imagination is important than knowledge
Answer:
frequency = 1475.45 Hz
Explanation:
given data
frequency f1 = 1215 Hz,
frequency f2 = 1265 Hz
police car moving vp = 25.0 m/s
solution
speed of sound u = 343 m / s
speed of the other car = v
when the police car is stationary
the frequency the other car receives is
f2 = f1 × 
................1
and
the frequency the police car receives is
f2 = f1 × 
..................2
now from equation 1 and 2
v = 4.77 m/s
and
frequency the other car receives is
f2 = f1 × 
......................3
and
the frequency the police car receives is
f2 = f1 × 
.......................4
now we get
f2 = f1 × 
f2 = 
f2 = 1475.45 Hz
Using the 3rd equation of motion:
= v² - u² = 2gs ------ [g = Acceleration due to gravity]
= v² - 20² = 2 × 10 × 300
= v² - 400 = 6000
= v² = 6000 - 400
= v = √5600
= v = 74.83 m/s
And yeah it's done :)
Answer:
Correct, is there another part to the question?
