Chapter 6
A 100kg car rounds a curved portion of the road at 20m/s. If the radius of the loop is 30m, what is the centripetal force on the car?
1.33e3 N
I do +12 J of work on a box over a time span of 6 seconds. Calculate power
2 Watts
The Kinetic energy of two carts before they collide is 20 J. When the collide they stick together.
After the collision which KE makes the most sense.
a. 20 J
b. -20 J
c. 5 J
d. 40 J
e. -5 J
f. -40 J
c. 5 J
I pull a lever with a force of 30 N a distance 10m from the axis of rotation, at an angle 10o. What is the magnitude of the torque?
52.09 Nm
The left side of a beam is attached to a hinge on a wall, and a string is attached to the right side of the beam. If I pull the string up what direction is the torque vector?
a. up
b. down
c. clockwise
d. counterclockwise
e. out of the page
f. into the page
e. out of the page
A disc with radius 10m is rotating with an angular velocity of 6 rad/s. How many revolutions does a point, 3m from the center make in 24s?
22.9 rev
If a box is released from rest from a 30m tall hill, what is the speed at the bottom? assume frictionless
24.3 m/s
An object has an initial momentum of 3 kg m/s and a final momentum of -4 kg m/s.
a. What is the impulse?
b. If the force applied was -300 N how long did the force act on the object?
a. -7 kg m/s
b. 0.0233 s
If I push a door with a force of 10 N a distance 3 m from it's hinge, what would the angle be to get maximum tourque, and what would the max tourque be?
angle = 90o
Max Torque = 30 Nm
A block is sliding across a rough sufrace. What is true of the system?
a. The force of friction is path independent
b. The system is conservative
c. The system is non-conservatitve
d. The system is path independent
e. All the above
f. None of the above
c
A 5kg ball is being spun in a horizontal circle by a string. The tension in the string is 20N. If the tangential speed of the ball is 3 m/s, what is the radius of the circle?
r=2.25m
A 2kg box is compressed 0.14m against a spring with spring constant 300 N/m. When the box is released form rest, what is its speed just after loosing contact with the spring?
1.71 m/s
Two people, Alice (50 kg) and Bob (70 kg), are standing on frictionless skateboards. Alice pushes Bob, giving him a velocity of +2 m/s. What is Alice’s velocity immediately after the push?
-2.8 m/s
Two children of mass 20.0 kg and 30.0 kg sit balanced on a seesaw with the pivot point located at the center of the seesaw. If the children are separated by a distance of 3.00 m, at what distance from the pivot point is the small child sitting in order to maintain the balance?
1.80 m
Which of the following is an example of a perfectly inelastic collision?
a. you shoot a bullet through a target
b. you bounce a ball off a wall
c. you roll a ball down a hill
d. you throw a dart at a target and they stick together
e. none of the above
d
Two masses are separated by a distance of 2.8*106 m. M1 has a mass of 3.52*105 kg, and M2 has a mass 1.68*109 g.
What is the magnitude of the force of M1 on M2, What about the force of M2 on M1?
The magnitude of both are 5.03*10-12 N.
A 2.3kg block slides down a ramp that is 30m long. At the base of the ramp is a spring. If the spring constant is 587 N/m, and the angle of the slope is 68 degrees above the horizontal then how much does the spring compress? Assume no friction
1.46 m
A 200g dart is thrown at a 20kg stationary target at a velocity of -9.3 m/s. If the dart sticks into the target what is the final speed of the dart/target combo?
-0.092 m/s
A person carries a plank of wood 2.00 m long with one hand pushing down on it at one end with a force F1 and the other hand holding it up at .500 m from the end of the plank with force F2. If the plank has a mass of 20.0 kg and its center of gravity is at the middle of the plank, what are the magnitudes of the forces F1 and F2?
F1 = 196 N
F2 = 392 N
If you spin a rock on a string in a horizontal circle, what is true? (there might be multiple correct answers, you need all of them)
a. The rock has constant speed
b. the rock has constant velocity
c. The tension in the string is equal to mv2/r
d. the direction of the stone's velocity does not change as it moves around the circle
e. the direction of the stone's velocity does change as it moves around the circle
a,c,e
A car of mass 1200 kg travels along a banked curve with a radius of 50 m. The road is banked at an angle of 20°. The coefficient of static friction between the tires and the road is 0.30.
a. What is the maximum speed the car can have without slipping up the bank?
b. What is the minimum speed the car can have without slipping down the bank?
a. 19.1 m/s
b. 5.2 m/s
A 49kg cart is released from rest from the top of a 300m tall roller coaster. The cart goes all the way down, then starts going up another hill.
a. What is the total mechanical energy?
b. What is the velocity of the cart when it is 50m up the second hill?
c. What is the Kinetic Energy at the bottom of the hill?
a. 1.44e5 J
b. 70 m/s
c. 1.44e5 J
A 87kg football player is running at you. Before you start running you shoot a 498g dart at the player. If the player was running at you at -8.55 m/s and you shot the dart at 15.83 m/s, calculate the final velocity of the dart as it bounces back at you elastically.
-32.7 m/s
A uniform ladder of mass 6.8kg and length 5.33m stands on a floor with friction and leans against a frictionless wall. A 86kg person stands 2.3m up the ladder. The base of the ladder is 2.22 m from the base of the wall.
What is the force of friction needed to keep the system in static equilibrium?
181.9 N
A uniform beam of length 4.0m is hinged at the left end to a wall. A rope is attahced to the free end of the beam and makes an angle of 30 degrees above the horizontal. A weight is hung from the beam 1.0 m from the wall. Which of the following is(are) true
a. The torque due to the rope about the hinge is clockwise
b. The torque due to the beams weight acts at a distance of 2 meters from the wall
c. The torque due to the hanging weight is counterclockwise
d. The torque vector caused by the rope is out of the page
e. A and D
f. B and D
g. A, B, C, and D
h. None of the above
f