physics_chapter6examples

physics_chapter6examples - Work done by a constant force...

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Work done by a constant force (a)Steve exerts a steady force of magnitude 210 N on a stalled car as he pushes it a distance of 18 m. The car also has a flat tire, so to make the car track straight Steve must push at an angle of 30° to the direction of motion. How much work does Steve do? = W Fscosφ = ( ) ° 210 N 18 m cos30 = 3274 J (b) In a helpful mood, Steve pushes a second stalled car with a steady force = ( ) - ( ) F 160 N i 40 N j . The displacement of the car is = ( ) + ( ) s 14m i 11 m j .How much work does Steve do in this case? = + W Fxx Fyy = +- ( ) 160 N14 m 40 N 11 m = 1800 J Work done by several forces A farmer hitches her tractor to a sled loaded with firewood and pulls it a distance of 20 m along level ground . The total weight of sled and load is 14,700 N. The tractor exerts a constant 5000-N force at an angle of 36.9° above the horizontal. There is a 3500-N friction force opposing the sled's motion. Find the work done by each force acting on the sled and the total work done
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physics_chapter6examples - Work done by a constant force...

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