They can't hear an echo in small room because in it the sound can't be reflected back. For an echo of a sound to be heard,the minimum distance between the source of sound and the walls of the roomshould be 17.2 m. Obviously,in asmall room echoes cannot beheard.
Answer:
1. 37.8J
2. 18 Billion Joules, 18 Gigajoules
3. 9.81 Billion Joules, 9.81 Gigajoules
Explanation:
Use the formulas provided,
KE=(1/2)mv^2 and PE=mgh, noting that g=9.81
Answer:
Friction always acts in the direction opposing motion. This means if friction is present, it counteracts and cancels some of the force causing the motion (if the object is being accelerated).
Explanation:
Friction is the force resisting the relative motion of solid surfaces, fluid layers, and material elements sliding against each other.
(d) Acceleration is a vector quantity
How bright a star appears from Earth is the star's apparent magnitude.
