Newton's first law can be taken to mean that if something is moving it tends to keep moving. if at rest it tends to stay at rest.
so, in a car, you and the car are both moving, say at constant speed. Now you're not actually connected to the car as in clamped to it, not yet at least. You're simply sitting in it at rest with respect to it.
but, someone slams on the brakes for whatever reason. The car slows down/stops. what do you do ? well, you would keep going. and moving a few feet in a car can be dangerous, esp if you're moving at high speed. Unless of course you're clamped to the seat, and the seat is clamped to the car and the car is clamped together. then when the car brakes, yes you'll feel the braking effect, but the belt will restrict your movement, keeping you safe, if shocked and bruised.
Answer:
The frequency heard by the motorist is 4313.2 Hz.
Explanation:
let f1 be the frequency emited by the police car and f2 be the frequency heard by the motorist, let v1 be the speed of the police car and v2 be the speed of the motorist and v = 343 m/s be the speed of sound.
because the police car is moving towards the motorist at a higher speed, then the motorist will hear a increasing frequency and according to Dopper effect, that frequency is given by:
f1 = [(v + v2/(v - v1))]×(f2)
= [( 343 + 30)/(343 - 36)]×(3550)
= 4313.2 Hz
Therefore, the frequency heard by the motorist is 4313.2 Hz.
The work done to push the refrigerator is 500 Nm.
Explanation:
Work done is the measure of force required to move any object from one point to another. So it is calculated as the product of force and displacement.
If the force increases the work done will increase and similarly, the increase in displacement increases the work done. So to push the refrigerator work should be done on the object and not by the object.
As the force is 100 N and the displacement is 5 m then, work done can be measured as
Work = Force × Displacement
Work = 100 × 5 = 500 Nm
So the work done to push the refrigerator is 500 Nm.
The pressure exerted on the block on the ground in N/m² is 200N/m².
<h3>What is pressure?</h3>
The pressure is the amount of force applied per unit area.
Given is a 5000 Newton block rests on the ground over 25 m² of area.
Pressure p = Force/Area
Put the values, we get
p = 5000 /25
p = 200 N/m²
Hence, pressure exerted on the block on the ground is 200 N/m².
Learn more about pressure.
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