Physics Questions & Answers

Physics Questions & Answers A 110 g hockey puck slides across the frictionless surface of an ice rink at 2.2 m/s. It collides with a 420 g water bottle at rest on the ice. The water bottle slides off at 0.84 m/s in the direction of the puck's original velocity. What is the puck's final velocity? - CORRECT ANSWER- 1.0 m/s opposite its original motion A 5-kg object is pushed across a floor with a force of 30 N to the right. It accelerates at 2 m/s2. What was the force of friction with the floor? - CORRECT ANSWER- 20 N to the left A ball is rolling across the floor at a constant speed. What will happen to the ball if it is exposed to an unbalanced force in the same direction that it is moving? - CORRECT ANSWER- Its speed will increase. A boy sits motionless partway down a playground slide. The force of friction balances the force of gravity. A girl hands the boy a book. Why does the boy still not move? - CORRECT ANSWER- The force of friction and the force due to gravity increase together. Friction and gravity are still balanced. A bucket of water is spun in a circle by a string attached to the handle of the bucket. If the string is 1 m long, what is the maximum possible displacement of the bucket from its starting position during two complete revolutions? - CORRECT ANSWER- 2 m A car suddenly slams on its brakes and skids west for 8 m before stopping. The force of friction acting on the car was directed - CORRECT ANSWER- east A certain chemical reaction takes roughly 1 minute to complete. If the reaction was run again, but the temperature and pressure of the reactants was lower, what would likely happen to the reaction rate? - CORRECT ANSWER- It would decrease. A certain object has 11 J of kinetic energy while traveling at 22 m/s. At what speed does it need to travel to have 15 J of kinetic energy? - CORRECT ANSWER- 26 m/s A classmate wonders whether her cell phone emits a strong magnetic field. Which of the following investigations could help answer this question? - CORRECT ANSWER- Measure the current in a piece of copper wire placed near the phone as the phone is turned on and off. A fisherman is watching water waves ripple past his boat. How could he determine the wavelength of the water waves? - CORRECT ANSWER- measure the distance between consecutive waves A football is thrown vertically with an initial velocity of 33 m/s. Calculate the velocity of the ball when its height has increased by 5 m. - CORRECT ANSWER- 31 m/s A friend claims that throwing a baseball up towards the school roof illustrates gravitational potential energy transforming into kinetic energy. What is wrong with your friend's statement? -