Only ' A ' is always true.<em> (choice-1)</em>
' B ' is not true when you drop a red hot spoon into cold soup.
' C ' is not true when you drop a red hot marble into a cool swimming pool.
Answer: 3 seconds
Explanation:
Initial velocity(u) of projectile A in vertical direction = 0m/s
acceleration due to gravity a=g=9.81m/s^2
Time taken(t) of projectile A = 3s
Initial velocity of projectile B = 0m/s(vertical direction)
We can get height of cliff using parameters of projectile A since it's the same location.
Height(S) = u×t + 0.5×a×t^2
u =0
S= 0.5×9.81×3^2 = 44.145m
Time taken for projectile B to reach the ground:
S = u×t + 0.5×a×t^2
u =0, S=44.145m, a=9.81m/s^2
44.145 = 0.5×9.81×t^2
44.145 = 4.905×t^2
44.145 ÷ 4.905 = t^2
9 = t^2
t = sqrt(9)
t = 3seconds
The crate’s acceleration is gravity= 9.81m/s^2
The ball’s acceleration is also gravity=9.81m/s^2
While the total energy<span> of a system is always conserved, the </span>kinetic energy<span> carried by the moving objects is not always conserved. In an inelastic collision, </span>energy<span> is </span>lost<span> to the environment, transferred into other forms such as heat.
Hope this helps.</span>
