Answer:
9.1m/s
Explanation:
Nate throws a straight ball to Kayla who is standing at a balcony 3.8m above Nate
When she catches the ball, it is still moving upward with a speed of 2.8m/s
v = 2.8m/s
u = ?
s = 3.8m
a= -9.8(The acceleration has a negative sign because the speed of the ball is declining)
Therefore the initial speed at which Nate threw the ball can be calculated as follows
v^2= u^2 + 2as
2.8^2= u^2 + 2(-9.8)(3.8)
7.84= u^2 + (-74.48)
7.84= u^2 - 74.48
u^2= 7.84 + 74.48
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u^2= 82.32
u= √82.32
u = 9.1m/s
Hence the initial speed at which Nate threw the ball is 9.1m/s
Answer:
the net force is 101587.5 N
Explanation:
The speed of wind
v = 30 m/s
The area of roof,
A = 175 m 2
The expression for the Bernoulli's theorem.
P = 12 ρv 2 ...... (1)
Here,
P is the pressure difference,
ρ is the density of air and
v is the speed of wind.
The expression for the pressure.
P = F A ..... (2)
Here,
F is the force and
A is the area of roof.
Part (a)
Substitute the values for the pressure difference in equation (1)
P = 12 × 1.29 × (30) 2 P = 580.5 Pa
Thus, the pressure difference at the roof between the inside and outside air is
580.5 Pa
Part (b)
Substitute the values for the net force in equation (2)
580.5 = F 175 F = 101587.5 N
Thus, the net force is 101587.5 N.
Answer:
Rutherford
Explanation:
Basic principles of the Rutherford atomic model.
1. Positively charged particles are in a very small volume compared to the size of the atom.
2. Most of the mass of the atom is in that small central volume. Rutherford did not call it "core" in his initial papal but he did it from 1912.
3. Electrons with negative electrical charge revolve around the nucleus.
4. The electrons rotate at high speeds around the nucleus and in circular paths that it called orbits.
5. Both negatively charged electrons and the positively charged nucleus are held together by an electrostatic attraction force.
