Physics 110 Model Midterm TEST 1. A bicycle travels 12 km in 40 min. Its average speed is : (Hint Vav d/t ; 1mi=1.6 km, 1km=1000 m ) a)0.3 km/h b)0.18 m/s c)11.25 mi/h d)5.1m/s e) None of these is true 2.A ball is thrown upward at 12m/s. What is its speed Is later? (g=9.8m/s) (hint V=Vogt; g=9.8 m/s2) a) 12m/s b)3.1m/s c)2.2m/s d)0.51m/s e) None of these is true 3. Two blocks (m=10kg, M=80kg) are pulled across the table by force 960N. The 10-kg block has a 20 N frictional force and the 80-kg block has a 40N frictional force. What is the acceleration (in m/s2 ) of the system? (Hint: F-fi-f2 =(m+M ) a ) a) 15 b) 12 c)10 d)6 e) None of these is true 4. The work done in lifting 45 1b bricks to a height of 20 ft is : W=mgh a) 1212 J b)900 J c)450 J d)125 J e) None of these is true 5. What is the speed of an 800 kg car whose kinetic energy mv2/2=250 kJ ? a) 253mi/h b)36 km/h c)25 m/s d) 12.5 cm/s e)None of these is true 6. A river flows due east at 2 m/s. A boat crosses the 300 m. wide river by maintaining a constant velocity of 10m/s due north relative to the water. If no correction is made for the current, how far downstream does he boat move by the time it reaches the far shore? a)6m b)30m c)60m d)90m e)100m 7. A sports car can accelerate from 0 to 63 mi/h in 4s. What is the magnitude of average acceleration (m/s-) of the car? a)3 b)4 c)6 d) 7 e)10 8. If a dropped ball falls 19.6 m in 2 s, how far will it fall in 4 s? a) 50 b)64 c)75 d)125 e) 150 9. A cart with weight 15000 N is moving around a curve with a radius 25 m with a speed of 35 m/s. What are the magnitude of the centripetal acceleration and the net force on the cart? a) 10 ; 15000 b)50; 750000 c)75; 100000 d)625, 175000 e)12, 180000 10. The acceleration of gravity on the surface of Jupiter is 3 g. What is the weight on Jupiter of a woman whose weight on Earth is 600 N? a)1500 b)1800 c)2000 d)2500 e)3000 1 1. A spring has a force constant k=1200 N/m. How far must the spring be stretched for 80 J of potential energy to be stored in it? Hint: U=kx2/2 a)0.15m b)0.120m c)0.4m d)0.25m e)0.10m 12. A 160 1b man dives horizontally from a 640 1b boat with a velocity of 6 ft/s . what is the recoil velocity of the boat? a) 1.5ft/s b)2.5 m/s c)3.2 m/s d)4.5ft/s e) 6.8 m/s