REVIEW A-C

A rescue plane wants to drop supplies to isolated mountain climbers on a rocky ridge 235 m below. If the plane is traveling horizontally with a speed of 250 km/h, how far in advance of the recipients (horizontal distance) must the goods be dropped?

• 481 m

• 235 m

• 121 m

• 605 m

• 69 m

A scout troop is practicing its orienteering skills with map and compass. First they walk due east for 1.2 km. Next, they walk 45° west of north for 2.7 km. In what direction must they walk to go directly back to their starting point? How far will they have to walk?

• 2.0 km at 20° east of south

• 2.0 km at 20° south of east

• 3.2 km at 30° east of south

• 3.2 km at 30° south of east

• 3.4 km at 45° north of west

A bicycle is moving along a straight line. The graph in the figure shows its position from the starting point as a function of time. In which section(s) of the graph does the object have the highest speed?

• AB

• BC

• CD

• DE

• EF

A 7180-kg helicopter accelerates upward at 0.8 m/s² while lifting a 1080-kg frame at a construction site. What is the lift force exerted by the air on the helicopter rotors? g = 9.80 m/s²

A 750-kg automobile is moving at 20.0 m/s at a height of 5.0 m above the bottom of a hill when it runs out of gasoline. The car coasts down the hill and then continues coasting up the other side until it comes to rest. Ignoring frictional forces and air resistance, what is the value of h, the highest position the car reaches above the bottom of the hill?

• 25 m

• 20 m

• 15 m

• 30 m

• 10 m

A 3.0-kg object is initially at rest. It then receives an impulse of magnitude 15 N·s. After the impulse, the object has

• a speed of 45 m/s.

• a momentum of magnitude 5.0 kg·m/s.

• a speed of 7.5 m/s.

• a momentum of magnitude 15 kg·m/s.

Find the center of mass of the object in the picture!

• (20, 30)

• (30, 20)

• (30, 40)

• (20, 40)

• (30, 30)

• 10.5%

• 89.5%

• 11.1%

• 88.9%

• 55%

The equation of a wave is seen in picture. Which statement is true?

• Amplitude of the wave is 3.5 m

• Wavelength of the wave is 3 cm

• Frequency of the wave is 33 Hz

• Period of the wave is 22 s

• Speed of the wave is 66 cm/s

A force F applied to each end of a steel wire (length L, diameter d) stretches it by 1.0 mm. How much does F stretch another steel wire, of length 2 L and diameter 2 d?

• 0.5 mm

• 1.0 mm

• 2.0 mm

• 4.0 mm

• 0.25 mm