Physics – 4.3a Net Force WS

1. Name_________________________ Hour_____ Physics – 4.3a Net Force WS Do this on a separate sheet • Determine your mass in kg noting that 1 kg is about 2.2 lbs. Then use Fg = mg to find your weight in Newtons. (Answers will vary.  ) • A 1100 kg car is to be given an acceleration of .27 m/s2 on a level road. How much force will be necessary? (297 N) • a) What force would be required for a 70 kg man to accelerate himself and his 20 kg bike at a rate of 2.5 m/s2? b) What would the force be if he decided to buy a bike made from Titanium that only had a mass of 11 kg? (225 N, 202.5 N) • A net force of 255 N accelerates an object at 4.2 m/s2. What is the object’s mass? (61 kg) • What is the weight of a 70 kg astronaut a) on the earth, b) on the moon (g = 1.7 m/s2), c) on Venus (g = 8.7 m/s2), and in outer space? (686 N, 119 N, 609 N, 0 N) • What constant force would be necessary to accelerate a 20 kg shopping cart from rest to 5 m/s in 2 seconds? (hint: find a like you would have in CH 2) (50 N) • What constant force is required to stop a 1000 kg car in 6 seconds if the car was initially traveling at 25 m/s? (4167 N in the opp dir) • A constant force acts on a 5 kg object and reduces its velocity from 7 m/s to 3 m/s over a 3 second time interval. What is the constant force required? (6.7 N in the opp dir) • A bus traveling 85 km/hr is brought to a stop in 135 m. If the weight of the bus is 22,000 N, what was the braking force? (Hint: Don’t forget to convert and you need to use a formula from CH 3) (4631 N in the opp dir) • What average force is needed to accelerate a 9.5 g bullet from rest to 500 m/s over a distance of .7 m along the barrel of a rifle? (Hint: Don’t forget to convert) (1696 N)