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Forces Worksheet #3 Newton’s Laws Problems Friction * 1. A box is resting on a flat surface. The box has a mass of 20 kg and a force of 200 N is pushing the box to the right. The force of friction acting on the box is 100 N to the left. a. Draw a picture of the box and show all the forces that are acting on the box. . b. What is the acceleration of the box? 2. A sled is loaded so that it has a weight of 600 N. It is being pulled by sled dogs that are exerting a force of 200 N to the right. The sled is moving at a constant velocity of 2 rn/s. a. What is the net force acting on the sled? / r’’ b. What is the coefficient of friction between the sled rails and the snowy surface? L 1 i& M 3. The sled now in #2 accelerates to the right at 4 rn/s 2 due to a change in the pulling force of the dogs that is now larger than before. a. What is the frictional force acting on the sled now? kF &( /&C — 0 b. What force must the sleddogs provide now to produce that acceleration? r f i_ F I I - 0,;/çJ — II1 I U_ / L4qJ L_Gic$ t’J The dogs pull so hard that the strap attached to the sled breaks. If the sled was moving at 6 rn/s when the straps broke c. What acceleration will be acting on the sled now? p r4 2 L a I £Z Z 20o F d. How much time will it take for the sled to stop and how far will it travel? -z---— Av’ 1 L- Vt 2 0 - F , ‘ix 1 ‘0 -2 t — 4 A 1500 kg cai is traveling at 100 km/hr along a flat road surface The car slams on its $* brakes and starts to slide. If the coefficient of sliding friction is 0.40, how far will the car travel prior to coming to a complete stop? 0 2 ‘v’F F - - It Z -fr I ‘F/ 5 & ô) Liz. %,LI,b, — o 5. A box of old, musty physics books is sitting in the corner of a room. The box has a mass of 50 kg. The coefficient of static friction between the floor and the box is 0.9. a. How much force must be used to get the box moving? r I V’ / I 1 I FqqIJ co - Uj ak \kqqj / b. How much force must be used to keep the box moving at a constant velocity if the coefficient of sliding friction is 0 5” • OS4 vn