Answer:
31.4 m/s
Explanation:
The Doppler equation describes how sound frequency depends on relative velocities:
fr = fs (c + vr)/(c + vs),
where fr is the frequency heard by the receiver,
fs is the frequency emitted at the source,
c is the speed of sound,
vr is the velocity of the receiver,
and vs is the velocity of the source.
Note: vr is positive if the receiver is moving towards the source, negative if away.
Conversely, vs is positive if the receiver is moving away from the source, and negative if towards.
Given:
fs = 1000 Hz
fr = 1100 Hz
c = 345 m/s
vr = 0 m/s
Find: vs
1100 = 1000 (345 + 0) / (345 + vs)
vs = -31.4
The speed of the car is 31.4 m/s.
Explanation:
From the curve given in the attachment,
a) minimum speed v0 required if the car is to travel beyond the top of the hill
climb to the top = 5.4 m
Therefore, 
= 10.29 m/s
b) No, we cannot affect this speed by changing the depth of the valley to make the coaster pick up more speed at the bottom as this speed does not depend upon depth of the valley.
Use Fnet=ma. Apply it to the vertical components of all the forces acting on the ball and since tension is the same on both wires you should be able to factor it out and solve for it. Picture below
A magnetic field is charged electricity acting in the forced of magnatism
