2A PHYS SAMPLE MIDTERM & Review 2
CLOSED BOOK Spring 2010
1. A 0.15 kg arrow is fired horizontally. The bowstring exerts a constant force pf 65 N on the arrow over a distance of 0.45 m. Determine: a) How much work is done by the bowstring on the arrow. b) The speed of the arrow when it leaves the bow.
2. A 2.00 kg crate starting at rest slides down a rough 5.00 m long ramp, inclined at 25 with the horizontal. If 20.0 J of energy is lost due to friction what is the speed of the crate at the bottom of the incline? a) 0.98 m/s b) 1.9 m/s c) 3.2 m/s d) 4.7 m/s e) 6.8 m/s
3. A 1000 kg sports car accelerates from zero to 25 m/s in 7.50 s. What is the average power delivered by the automobile engine? a) 27.9 hp b) 40.6 hp c) 55.9 hp d) 70.2 hp e) 82.4 hp (Recall 1hp = 746 W)
4. Alex throws a 0.15 kg rubber ball down onto the floor. The ball's speed just before impact is 6.5 m/s downward, and just after is 3.5 m/s upward. IF the ball is in contact with the floor for 0.025 s, what is the magnitude of the average force of the floor on the ball? a) 60 N b) 133 N c) 3.0 N d) 3.5 N e) 600 N
5. Ball 1 traveling at 4.0 m/s to the right collides with Ball 2 that is traveling to the right at 1.0 m/s. After the collision Ball 1 is traveling the to left at 1.00 m/s. If the collision is elastic: a) Find the direction and velocity of ball 2 after the collision. (m/s) b) Are the masses of the two balls the same and why or why not?
2 6. A record is rotating at 33 rpm. The motor is turned off and the record comes to a stop at constant deceleration in 2.5 min. Determine: a) The angular deceleration. (rad/sec2) b) The initial speed at 8.00 cm from the center of the record. (cm/s) c) The number of revolutions the record makes before stopping. (rev)
7.
A car rounds a corner of radius r= 45 m. If the coefficient of static friction between the car and the road is = 0.82, what is the greatest speed the car can have in the corner without skidding?
8. A car has a constant speed of 17.0 m/s on a road. The car goes through a dip in the road whose radius of curvature is 65.0 m. For the 1800 kg car during the dip determine: a) The centripetal force acting on the car. b) The normal force acting on the car.
9.
The escape speed from the surface of Earth is 11.2 km/s. Estimate the escape speed for a spacecraft from the surface of the Moon. The Moon has a mass 1/81 that of Earth and a radius 0.25 that of Earth. Recall for the Earth vescape=(2GME/RE)1/2 (a) 0.25 km/s (b) 4.0 km/s (c) 5.6 km/s (d) 8.7 km/s