Answer:
a) In order to catch the ball at the level at which it is thrown in the direction of motion.
b)Speed of the receiver will be 7.52m/s
Explanation:
Calculating range,R= Vo^2Sin2theta/g
R= (20^2×Sin(2×30)/9.8 = 35.35m
Let receiver be(R-20) = 35.35-20= 15.35m
The horizontal component of the ball is:
Vox= Vocostheta= 20× cos30°
Vox= 17.32m/s
Time taken to coverR=35.35m with 17.32m/s will be:
t=R/Vox= 35.35/17.32
t= 2.04seconds
b)Speed required to cover 15.35m at 2.04seconds
Vxreciever= d/t = 15.35/2.04 = 7.52m/s
4.Use Ohm’s Law to determine the resistance in a circuit if the voltage is 12.0 volts and the current is 4.0 amps.
A. 8.0 ohms B. 48 ohms C. 3.0 ohms D. 12 ohms
Ohm's law is V=IR, or I=V/R, or R=V/I. (I= current, V= voltage, R= resistance.) Let's plug in our variables: V=12.0, I=4.0, R=? into the equation R=V/I. 12.0/4.0=3.0, so the resistance is 3.0 ohms.
The potential difference,electric current ,resistance and new electric current will be 12 V,4 A,3 Ω,2 A.
<h3>What is resistance?</h3>
Resistance is a type of opposition force due to which the flow of current is reduced in the material or wire. Resistance is the enemy of the flow of current.
The energy in terms of the charge and potential difference is;
E= qV
60=5 C × V
V= 12 V
The electric current is found as;

From the ohm's law;
V=IR
12=4 ×R
R=3Ω
If the voltage is constant and the resistance is doubled, then the new electric current is half of the previous condition;

Hence, the potential difference,electric current ,resistance and new electric current will be 12 V,4 A,3 Ω,2 A.
To learn more about the resistance, refer to the link;
brainly.com/question/20708652
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Answer:
<h2>1/7 kg</h2>
Explanation:
Find the diagram attached for better understanding of the question.
Given the mass of one of the blocks to be 1.0kg and accelerates downward at 3/4g.
g = acceleration due to gravity.
Let the block accelerating downward be M, mass of the other body be 'm' and the acceleration of the body M be 'a'.
M = 1.0 kg and a = 3.4g
According to newton's second law; 
For body of mass m;
T - mg = ma ... (1)
For body of mass M;
Mg - T = Ma ... (2)
Adding equation 1 ad 2;
+Mg -mg = ma + Ma
Ma-Mg = -mg-ma
M(a-g) = -m(a+g)
Substituting M = 1.0 kg and a = 3/4g into the resulting equation;
3/4 g-g = -m(3/4 g+g)
3/4 g-g = -m(7/4 g)
-g/4 = -m(7/4 g)
1/4 = 7m/4
28m = 4
m = 1/7 kg
Therefore the mass of the other box is 1/7 kg
Answer:
The amplitude of the oscillating electric field is 1316.96 N/C
Explanation:
Given;
frequency of the wave, f = 2.4 Hz
intensity of the wave, I = 2300 W/m²
Amplitude of oscillating magnetic field is given by;

where;
μ₀ is permeability of free space = 4π x 10⁻⁷ m/A
I is intensity of wave
c is speed of light = 3 x 10⁸ m/s

The amplitude of the oscillating electric field is given by;
E₀ = cB₀
E₀ = 3 x 10⁸ x 4.3899 x 10⁻⁶
E₀ = 1316.96 N/C
Therefore, the amplitude of the oscillating electric field is 1316.96 N/C