Answer:
7,546 J
Explanation:
recall that Potential energy is given by
P.E = mgΔh
where m = 70kg (given)
g = 9.8 m/s² (acceleration due to gravity)
Δh = change in height
= distance from top of building to top of car
= height of building - height of car
= (5+8) - 2
= 11m
substituting all these into the equation:
P.E = mgΔh
= 70 x 9.8 x 11
= 7,546 J
Answer:
The work done by this force can be found via the following formula

Explanation:
Alternatively, the work done by the object is equal to the elastic potantial energy done by the spring.

The maximum force acts between B and C as the graph is steepest showing maximum deceleration
Answer:B)439.21 Hz
Explanation:
Given
velocity of train 
frequency of train 
speed of sound 
frequency from Doppler effect can be calculated by




