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Questions in physics

[Done] Define an ideal simple pendulum. Show that its motion under certain conditions is simple harmonic. Derive an expression for its period.

[Done] How much work do you need to do if you use a force of 3 Newtons to move a table 25 meters?

[Done] A hot air balloon along with its basket and contents has mass M. It is descending at a constant acceleration a less than the acceleration due to gravity. When the content of mass m is released from the hot air balloon, it starts rising upwards with the acceleration of same magnitude a. What is the value of m? (A) \frac{\alpha}{M(a+g)} (B) \frac{2\alpha}{M(a+g)} (C) \frac{\alpha+g}{M\alpha} (D) \frac{2\alpha}{M(a+g)}

[Done] If a lamp transforms 120 joules of energy into light and heat every 2 seconds, how much power does it use? A. 240 W B. 480 W C. 120 W D. 60 W

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

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

[Done] Which phrase describes an irregular galaxy? A. has a round shape B. does not have a specific shape C. has arms that extend from the center D. is larger than other types of galaxies

[Done] The potential energy, [tex]$P$[/tex], in a spring is represented using the formula [tex]$P=\frac{1}{2} k x^2$[/tex]. Lupe uses an equivalent equation, which is solved for [tex]$k$[/tex], to determine the answers to her homework. Which equation should she use? [tex]$k=2 P x^2$[/tex] [tex]$k=\frac{1}{2} P x^2$[/tex] [tex]$k=\frac{2 P}{x^2}$[/tex] [tex]$k=\frac{P}{2 x^2}$[/tex]

[Done] Which one of the following accurately describes the universal gravitational law? A. Solid bodies attract other solid bodies, but liquid and gas don't participate in universal gravitation. B. As the distance between any two bodies increases, the gravitational force between them decreases. C. Objects with small masses have more gravitational attraction to each other than objects with large masses. D. Every object that has mass attracts other objects within a million-mile radius.

[Done] Two balls are projected simultaneously, one from the top and the other from the bottom of a building as shown below. The ball does not bounce back after hitting the ground. Find the time after which ball A and ball B collide. ↑ 30 m/s (Ball B from bottom) 20 m (height of building) ↓ 40 m/s (Ball A from top)