This preview has intentionally blurred sections. Sign up to view the full version.
View Full DocumentThis preview has intentionally blurred sections. Sign up to view the full version.
View Full DocumentThis preview has intentionally blurred sections. Sign up to view the full version.
View Full Document
Unformatted text preview: . A mass M = 5.6 kg on a horizontal table is pulled by a horizontal string
that passes over a frictionless pulley to e freehanging mass m = 3.4 kg. The _
coefﬁcient of friction between M and the table is 0.28. The acceleration of
M is “r — ' 3.7 m/s2
2.0 In/s2
2.2 m/s2
0.20 m/s2
0149 m/s2 . A 50kg box is placed in the bed of a truck. The coefﬁcient of friction
. between the box and the truck bed is 0.54. If the truck is traveling at 87 km/ h ($54 mph) then calculate the minimum distance the truck can stop in without the box sliding into the cab. Assume that the truck changes its
velocity at a. constant rate ‘ — ; 99m ‘
1.4 x 103m 55171. 1.2 x 102m 2.3 x 10% Two skiers start at the top of a. hill asuthe same place (P1) and ﬁnish at the
bottom of the hill, also at the same place (P2). Skier A takes a straight,
smooth route to the ﬁnish whereas Skier B takes a. curvy, bumpy route to
the ﬁnish. If you assume that friction is negligible, which of the following
statements is true? Skier A has the some speed as skier B at the ﬁnish. Skier B has the greater speed at the ﬁnish. Skier A has the greater speed at the ﬁnish because the route is
straight. Skier A has the greater speed at the ﬁnish because the route is
smooth. Skier A has the greater speed at the ﬁnish because the route is both
straight and smooth. l
4. A Blackhawk helicopter is winching up an injured soldier from a danger
zone. The soldier and his kit have a mess of 150 kg and are pulled up 51 in
in the aired; a steady rate. If it takes 30 s to pull the soldier up, how much 'power has been used by the helicopter’s winch engine (assume no power
losses in the engine)? 1.63 kW
2.5 kW
1.0 kW
2.7 kW
2.1 kW 5. A block of mass m is pushed up against a spring, compressing it a distance
x, and is then released. The spring projects the block along a frictionless
horizontal surface, giving the block a speed v. The same spring projects
a second block of mass 4m, giving it a speed 3v. What distance was the
spring compressed in the second case? ._ F" x
2x
3x
4x .
6x 6. See Fig. A below. Release mass m 011 a string from rest at point A. As it
passes the lowest point B, the tension in the string is impossible to determine; the answer depends on the length of the
string. — 111g 2mg 3mg in. ' WC — —‘ None of these is correct. An astronaut lands on an earthlike planet and drops a. small lead ball with
a mass of 76.5 g from the top of her spaceship. The point of release is 18 m
above the surface of the planet and the ball takes 2.5 s to reach the ground.
The astronaut’s mass on earth is 68.5 kg. Her weight on the planet is I 1
69.0 N
395 N
670 N
990 N
1.02 kN 10. 11. ’ If the only forces acting 011 a 2.0kg mass are F1 = (3i—8j) N and F2 = (5i +‘3j)‘ N, What is the magnitude of the acceleration of the particle? 1.5 m/s2
6.5 ru/s2
4.7 m/s2
9.4 m/s2
7.2 rn/s2 \ See Fig. B below. The horizontal surface on which the objects slide is
frictionless. If M : 2.0 kg, the tension in string 1 is 12 N. Determine F. 25N
I 2ON
SON
35N
40N ‘ Til/f" l‘l “" ' " § 7 "7
See Fig. C below. A rollercoaster car has a masssof 500 kg when fully
loaded with passengers. The ear passes over a hill of radius 15 In, as shown.
At the top of the hill, the car has a speed of 8.0 m/s. What is the force of
the track on the car at the top of the hill? _ l .7 7.0 kN up
7.0 kN down
2.8 kN down
2.8 kN up
5.6 kN down When a car goes around a circular curve on a level road, no frictional force is needed because the car Simply follows the road.
the frictional force of the road on the car increases when the car’s
speed decreases. '
the frictional force of the road on the car increases when the car’s
speed increases. the frictional force of the road on the car increases when the car
moves to the outside of the curve. there is no net frictional force because the road and the car exert
equal and opposite forces on each other. 12. 13. 14. l
The force an ideal spring exerts on an object is given by F;r = —k:t, where
3: measures the displabement‘ of the object from its equilibrium (x : 0) p'osition.‘ If k '=_60 N/m, ,how‘much work is done by this force as the object
moves from x = 43.20 m to X = 0? . 1.2 J +1.2 J +2.4J‘ ' 2.4 J +3.6 J . ‘ “‘Rm .0 The speed of a 4.0»kg object is given by v = (2t) m/s, where t is in 5. At
what rate is the resultant force on this object doing work at t : 1 s? 48W
40w
32w‘
56W
16W . . J .
See Fig. D below. _The horizontal surface on which the block slides is
frictionless: The speed of the block before it touches the spring is 6.0 m/s.
How fast is the_block moving at the instant the spring has been compressed _ 15 cm? The spring constant k is 2.0 kN/m and the mass of the block is 2.0 ks. 3.7 m/s
4.4 m/s
4.9 rn/s
5.4 m/s
14 m/s n. 15.‘ See Fig. E below. A 0.04kg ball is thrown from the top of a 30m tall
building (point A) at an unknown angle above the horizontal. As shown in
the ﬁgure, the bell attains a maximum height of 10 In above the top of the
building before striking the ground at point B. If air resistance is negligible,
what is the value of the kinetic energy of the ball at B minus the kinetic
energy of the ball at A (KB — KA)? ' 12 J
12 J
20 J
20 J
32 J Some possibly useful information:
9 = 9.80 711/52
1 mile 2 1.609 km Figure B (Problem 9) (the masses are, from ’51:: left, M, 2M and 2M, the strings are labeled “2” and “1”, again from the leﬁ, andf is the force at the right of the ﬁgure) la: C V Figure C (Problem 10) Figure D (Problem 14) Figure B (Problem 15) ...
View
Full Document
 Fall '07
 Bartynsky

Click to edit the document details