# Physics

posted by .

A police radar has an effective range of 1.0 km, and a motorist's radar detector has a range of 1.9 km. The motorist is going 100km/h in a 80km/h zone when the radar detector beeps. At what rate must the motorist decelerate to avoid a speeding ticket?

• Physics -

Find: a
Given:
s = (1.9-1.0)[km]
u = 100[km/h]
v = 80[km/h]
Using two equations:
<1>: s = u t + ½ a t²
<2>: v = u + a t

Rearrange <2> to get t.
t = (v-u)/a

Substitute this into <1> to get a.
s = u(v-u)/a + (v-u)²/(2a)

Rearrange
.: a = (v²-u²)/(2s)

Calculate using the given values.
I suggest converting from [km/h²] to [m/s²]

• Physics -

34

## Similar Questions

1. ### crim j

Defendant A was suspected of selling stolen property from his dorm room. An undercover campus police officer knocked on Defendant A’s door. And when answer, asked for an affordable radar detector. In response, defendant A said that …
2. ### college

Defendant A was suspected of selling stolen property from his dorm room. An undercover campus police officer knocked on Defendant A’s door. And when answer, asked for an affordable radar detector. In response, defendant A said that …
3. ### Math

Can someone please go over the steps to solve this problem?

(Airplane & Radar) An airplane is flying (horizontally) at the height of 6 km on a flight path that will take it directly over a radar tracking station (on ground). If the distance D between the plane and the radar is decreasing at …
5. ### Caculas

(Airplane & Radar) An airplane is flying (horizontally) at the height of 6 km on a flight path that will take it directly over a radar tracking station (on ground). If the distance D between the plane and the radar is decreasing at …
6. ### Physics

A motorist traveling at 30 m/s passes a parked police car. At the instant the motorist passes the police car, the police car starts chasing the motorist with an acceleration of 3 m/s^2. How far does the police car have to travel to …
7. ### Science

1. A certain radar installation transmits electromagnetic radiation with a wavelength of 2.5 cm. What is the frequency of this radiation?
8. ### biology

9. A certain radar installation transmits electromagnetic radiation with a wavelength of 2.5 cm. What is the frequency of this radiation?
9. ### Maths-Geometry(Loci)

A port has two radar stations at P and Q which are 20 km apart.The radar at P is set to a range of 20 km,whilst the radar at Q is set to a range of 15 km. a)draw a scale diagram to show the above information b)Shade the region in which …
10. ### Maths

A port has two radar stations at P and Q which are 20 km apart.The radar at P is set to a range of 20 km,whilst the radar at Q is set to a range of 15 km. a)draw a scale diagram to show the above information b)Shade the region in which …

More Similar Questions