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An object has a kinetic energy of 231 J and a momentum of magnitude 26.8 kgm/s. Find the speed and the mass of the object. speed -------- m/s mass...

this is a physics question see if you can help...appreciate it. 

1. An object has a kinetic energy of 231 J and a momentum of magnitude 26.8 kg · m/s. Find the speed and the mass of the object. speed -------- m/s mass ----------- kg 2. At one instant, a 15.0 -kg sled is moving over a horizontal surface of snow at 4.60 m/s. After 6.05 s has elapsed, the sled stops. Use a momentum approach to ±nd the magnitude of the average friction force acting on the sled while it was moving. -------------- N 3. A 45.8 -kg girl is standing on a 153 -kg plank. Both originally at rest on a frozen lake that constitutes a frictionless, ²at surface. The girl begins to walk along the plank at a constant velocity of 1.58 î m/s relative to the plank. (a) What is the velocity of the plank relative to the ice surface? -------------- î m/s (b) What is the girl's velocity relative to the ice surface? ------------- î m/s 4. A man claims that he can hold onto a 16.0 -kg child in a head-on collision as long as he has his seat belt on. Consider this man in a collision in which he is in one of two identical cars each traveling toward the other at 62.0 mi/h relative to the ground. The car in which he rides is brought to rest in 0.08 s. (a) Find the magnitude of the average force needed to hold onto the child. -------------- N (b) Based on your result to part (a), is the man's claim valid? ----------- This man's claim is nonsense. ------------ This man's claim is legitimate. 5. An estimated force–time curve for a baseball struck by a bat is shown in the ±gure below. Let F max = 16,000 N, t a = 1.5 ms, and t b = 2 ms. From this curve, determine the following.
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(a) the magnitude of the impulse delivered to the ball -------------- N · s (b) the average force exerted on the ball ------------------- kN 6. After a 0.320 -kg rubber ball is dropped from a height of 18.5 m, it bounces oF a concrete ±oor and rebounds to a height of 15.0 m. (a) Determine the magnitude and direction of the impulse delivered to the ball by the ±oor. magnitude ----------- kg · m/s direction ---Select--- right left up down (b) Estimate the time the ball is in contact with the ±oor to be 0.04 seconds. Calculate the average force the ±oor exerts on the ball. magnitude ---------- N direction ---Select--- right left up down 7. . In a slow-pitch softball game, a 0.200-kg softball crosses the plate at 19.0 m/s at an angle of 40.0 ° below the horizontal. The batter hits the ball toward center ²eld, giving it a velocity of 46.0 m/s at 30.0° above the horizontal. (Take positive î to be the horizontal direction from the plate toward center ²eld and take positive ĵ to be the upward vertical direction.) (a) Determine the impulse delivered to the ball. = ----------------- N.s (b) If the force on the ball increases linearly for 4.00 ms, holds constant for 20.0 ms, and then decreases linearly to zero in another 4.00 ms, what is the maximum force on the ball? = --------------- N 8.
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