Answer:
21.8 m/s
Explanation:
At the top of the hill (crest), there are two forces acting on the motorcycle:
- The reaction force of the road, N (upward)
- The force of gravity, mg (downward)
Since the motorcycle is moving by circular motion, the resultant of these forces will give the centripetal force, so:

where the direction of the weight (mg) is equal to that of the centripetal force, and where
m is the mass of the cycle
g = 9.8 m/s^2 is the acceleration of gravity
v is the speed
r = 48.6 is the radius of the hill
The cycle loses contact with the road when the reaction force becomes zero:
N = 0
Substituting into the equation, we therefore find the maximum speed that is allowed for the cycle before losing constact:

Answer:
Δt = 5.29 x 10⁻⁴ s = 0.529 ms
Explanation:
The simple formula of the distance covered in uniform motion can be used to find the interval between when the sound arrives at the right ear and the sound arrives at the left ear.

where,
Δt = required time interval = ?
Δs = distance between ears = 18 cm = 0.18 m
v = speed of sound = 340 m/s
Therefore,

<u>Δt = 5.29 x 10⁻⁴ s = 0.529 ms</u>
Given
The projectile is in air for a time of t=8 sec
To find
The time it takes to reach the highest point
Explanation
A projectile moves up to the highest point and then again moves down following a parabolic path.
So it will reach the highest point at a time half the time it requires to follow teh parabolic path.
The time taken to reach the highest point is 4 sec
Conclusion
The time taken is 4 sec.