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Questions in physics

[Free] A quarterback throws a football to a teammate. The football is 6.5 ft above the ground when it leaves the quarterback's hand. His teammate catches it 3.5 s later, at a height above the ground of 5 ft. Projectile motion formula [tex]\begin{array}{l} h(t)=-16 t^2+v t+h_0 \\ h_0=6.5 \\ v=? \\ h=5 \text { when } t=3.5 \end{array}[/tex] Determine the value of [tex]v[/tex], rounded to the nearest whole number. [tex]v \approx[/tex] $\square$

[Free] Part A The eccentricity of Earth's orbit can be found using this equation: [tex]$e=\frac{a-p}{a+p}$[/tex] As recently as 350,000 years ago, Earth's orbit had an eccentricity of approximately 0. What does this fact tell you about the relative distances between Earth and the Sun during aphelion and perihelion?

[Free] An electric device delivers a current of [tex]$15.0 A$[/tex] for 30 seconds. How many electrons flow through it?

[Free] Let's try a problem. You heat 2.0 kg of water to make pasta. The temperature of the water before you heat it is [tex]$40^{\circ} C$[/tex]. The temperature of the water after you heat it is [tex]$100^{\circ} C$[/tex]. How much heat was transferred to the water? (The specific heat of water is [tex]$4,184 J / kg \cdot{ }^{\circ} C$[/tex]). Step 1: Write the equation. heat = specific heat [tex]$\times$[/tex] mass [tex]$\times$[/tex] change in temperature Step 2: Place values into the equation, and solve. [tex]$\text { heat }=4,184 J / kg \cdot{ }^{\circ} C \times 2.0 kg \times\left(100^{\circ} C-40^{\circ} C\right)=502,080 J . $[/tex] The heat transferred is [tex]$502,080 J$[/tex]. Calculate Use the data in the figure to determine the energy needed to warm the water in the cup.

[Free] Which statement describes Newton's law of universal gravitation? A. Mass has little effect on gravity between objects. B. Gravity pushes objects away from Earth's center. C. Gravity does not act between Earth and the moon. D. Every object in the universe attracts every other object.

[Free] A jogger sprints 100 m in 13 seconds. What is her average speed?

[Free] Does sound travel faster in a warm room or a cold room? Explain your answer.

[Free] What is the main difference between protons and neutrons? A. Protons have a much smaller mass than neutrons. B. Protons have a much larger volume than neutrons. C. Protons have an electrical charge, but neutrons have no charge. D. Protons make up the nucleus, but neutrons orbit around the nucleus.

[Free] An electric device delivers a current of [tex]$15.0 A$[/tex] for 30 seconds. How many electrons flow through it?

[Free] Which best explains why replicating an experiment should be done by someone other than the person who originally did the experiment? A. It shows that the results are the same using different methods. B. It shows that the experiment is easy to do. C. It shows that the results are as expected. D. It shows that the experiment is designed properly.