Answer:
55.8 m/s
Explanation:
= Actual frequency of sound emitted by car
= frequency observed when the car moves = 
= Speed of sound = 343 m/s
= Speed of car
Frequency observed is given as
Answer: To increase the rigidity of the system you could hold the ruler at its midpoint so that the part of the ruler that oscillates is half as long as in the original experiment.
Explanation:
When a rule is displaced from its vertical position, it oscillates back and forth because of the restoring force opposing the displacement. That is, when the rule is on the left there is a force to the right.
By holding a ruler with one hand and deforming it with the other a force is generated in the opposite direction which is known as the restoring force. The restoring force causes the ruler to move back toward its stable equilibrium position, where the net force on it is zero. The momentum gained causes the ruler to move to the right leading to opposite deformation. This moves the ruler again to the left. The whole process is repeated until dissipative forces reduce the motion causing the ruler to come to rest.
The relationship between restoring force and displacement was described by Hooke's law. This states that displacement or deformation is directly proportional to the deforming force applied.
F= -kx, where,
F= restoring force
x= displacement or deformation
k= constant related to the rigidity of the system.
Therefore, the larger the force constant, the greater the restoring force, and the stiffer the system.
To solve this problem it is necessary to apply the definition of severity of Newtonian laws in which it is specified that gravity is defined by
Where
G= Gravitational Constant
M = Mass of Earth
R= Radius from center of the planet
According to the information we need to find the gravity 350km more than the radius of Earth, then
Therefore the gravitational acceleration at 350km is 
