Answer:
98 m √
Explanation:
How about s = Vo * t + ½at² ?
s = h = Vo * 2s - 4.9m/s² * (2s)² = 2Vo - 19.6
and
h = Vo * 10s - 4.9m/s² * (10s)² = 10Vo - 490
Subtract 2nd from first:
0 = -8Vo + 470.4
Vo = 58.8 m/s
h = 58.8m/s * 2s - 4.9m/s² * (2s)² = 98 m
Answer:
B) 
Explanation:
The electric force between charges can be determined by;
F = 
Where: F is the force, k is the Coulomb's constant, 
is the value of the first charge, 
is the value of the second charge, r is the distance between the centers of the charges.
Let the original charge be represented by q, so that;
= 2q
= 
So that,
F = x 
= 2q x x
= 
x
= x 
F = x
The electric force between the given charges would change by .
Answer:
The frequency of the phonograph record is 0.2 Hz
Explanation:
The frequency of an object moving in uniform circular motion is the number of completed cycles the object makes in a specified time period
The given parameters of the phonograph record are;
The radius of the record = 0.15 m
The number of times the phonograph record rotates, n = 18 times
The time it takes the phonograph record to rotate the 18 times, t = 90 seconds
The frequency of the phonograph record, f = (The number of times the phonograph record rotates) ÷ (The time it takes the phonograph record to rotate the 18 times)
∴ The frequency of the phonograph record, f = n/t = 18/(90 s) = 0.2 Hz
The frequency of the phonograph record = 0.2 Hz.
Answer:
-1.43 m/s relative to the shore
Explanation:
Total momentum must be conserved before and after the run. Since they were both stationary before, their total speed, and momentum, is 0, so is the total momentum after the run off:
where 
are the mass of the swimmer and raft, respectively. 
are the velocities of the swimmer and the raft after the run, respectively. We can solve for 
So the recoil velocity that the raft would have is -1.43 m/s after the swimmer runs off, relative to the shore
