A force is applied to an object as shown. What is the direction of the torque vector?
(Ans- into the screen
The integral (squiggle)dt is called the angular impulse. It is equal to
(Ans- the change in angular momentum
A truck weighing 1000 N moves at 5.89 m / s when it has an elastic colli...
PHYS Exam: Questions & Answers
(Straighterline)
A force is applied to an object as shown. What is the direction of the torque
vector?
(Ans- into the screen
The integral (squiggle)dt is called the angular impulse. It is equal to
(Ans- the change in angular momentum
A truck weighing 1000 N moves at 5.89 m / s when it has an elastic
collision with another vehicle. The second vehicle, weighing 981 N, was
stationary but free to move. Which of the following is the final velocity of the
first vehicle after the collision?
(Ans- v1 f = 0.0565 m / s
Which of the following statements concerning an object in free fall through
the atmosphere is incorrect?
(Ans- The speed of a falling object increases due to the frictional force of
air drag.
Which of the following is not an example of a vector?
(Ans- mass
If two objects with the same radius, one with I1 = I and the other with I2 =
2I, both roll down an incline, which would reach the ground first?
(Ans- The object with I1 = I.
A train is on an incline and has a mass of 2.36 × 103 kg. It initially coasts at
27.8 m/s. Which of the following is the speed of the train at position B.
Assume no additional assistance from the engine.
(Ans- 34.2 m/s
,A point mass m is hung on an ideal, massless rod of length z. A torque of
magnitude r is applied to the system about P, displacing it as shown. What
is the horizontal displacement L of the mass from vertical?
(Ans- r/mg
A stunt man is sliding down the side of a mountain when he manages to
catch a tree with a wristwatch winch, which supplies a constant tension, T.
Neglecting air friction, if the mountain slope is inclined at an angle θ, what
is the acceleration of the stuntman?
(Ans- -T / m + g sin θ
Given the vector A as shown in the figure, select the choice that gives the
vector's correct description in component form.
(Ans- Ax = Acos0 Ay = Asin0
You are going for a bike ride. You ride down a straight road at a speed of
9.0 mi / hr. Just as you pass the point which is 3.6 miles from your starting
point, you develop a flat tire. You get off you bike and walk it to a bike shop
0.5 mile further down the road. The walk to the bike shop takes 12 minutes.
What was your average velocity for the entire trip?
(Ans- 6.8 mi / hr
An empty freight train car of mass 10,000 kg is rolling along a level section
of track at 2.00 m / s. It collides with a loaded car of weight 1.96 × 105 N,
which is at rest. The cars couple upon collision. Which of the following is
the speed of the train after the collision?
(Ans- 0.667 m / s
A 1,450 kg car moves with a speed of 25.0 m / s when it collides with a
stationary car having a mass of 1,550 kg. The two vehicles lock bumpers
on impact. The two cars then collide with a stationary third car of mass
1,250 kg. During this second impact, the third vehicle becomes attached to
the second but the first car is breaks free and moves at 0.125 m / s in the
opposite direction. Which of the following is the final velocity of the second
and third cars after the final collision? (Ans- 13.01 m / s
,A 200 g plastic ball is at rest on a frictionless incline 0.658 m above the
surface of a table. The ball then rolls down the incline and across the table,
coming to rest after a distance of 2.45 m. Which of the following the
average friction on the ball while rolling across the table.
(Ans- 0.527 N
A power company charges its customers for electricity based upon which
one of the following?
(Ans- energy
Car 1 of mass 700 kg is slowly moving along at 0.500 m / s when it is hit
from behind by car 2 speeding along at 15.0 m / s. After collision, car 1 has
a new speed of 8.00 m / s in the same direction. Which of the following is
the force with which car 2 must have struck car 1, if the collision lasted for
0.932 s? Also, knowing that conservation of momentum applies to the
situation, what is car 2's speed after the collision (v2 f ) if it has a mass of
850 kg?
(Ans- F = 5.63 × 103 N
v2 f = 8.82 m / s
A motorcycle is moving with a speed of 8.3 m / s when it begins to brake
and slow down at a constant rate. If the acceleration is 3.1 m / s2, how
much further will the motorcycle travel before it comes to a complete stop?
(Ans- 11 m
Where does the concept of moment of inertia come from?
(Ans- Rotational kinetic energy
Two children are playing catch in a passenger train. An observer on the
ground measures that the train is traveling at 70 mph. As the train passes
the observer, he measures that the ball is thrown with half of the speed as
the passenger train. What velocity do the children measure for the ball?
(Assume the positive direction is the direction in which the train is moving.)
(Ans- −35 mph
, How fast must a baseball move as it leaves your hand if it reaches a
maximum height of 15.0 m above the point where it left your hand?
(Ans- 17.1 m / s
A truck that weighs 1000 N moves at 5.89 m / s when it hits another vehicle
in an elastic collision. The second vehicle, weighing 981 N, was stationary
but free to move. Find the final velocity of the second vehicle after the
collision.
(Ans- v2 f = 5.95 m / s
A binary star system consists of two identical stars moving in circular orbits
around the system's center of mass (see the diagram). The mass of each
star is M and the radius of the orbit is R. Which expression correctly gives
the orbital speed for one of the stars?
(Ans- (GM/4R)1/2
Consider a spring that is stretched from its equilibrium position x0, where
x0 = 0, to a position x, where x is positive. Which of the following describes
why the work done by a spring is negative?
(Ans- All of the choices are correct.
When designing elevators, it is important to consider the maximum tension
a cable will support. Which of the following causes a maximum tension?
(Ans- accelerating upward
Which of the following is the gravitational force between the Earth and the
Moon? The Earth's mass is 6x10 24 kg, the moon's mass is 7.4 x 10 22 kg,
and the distance between the centers of mass is 3.8 x 10 8 m.
(Ans- 2.1 x 10 20 N
Given the vectors A = 6i + 3j and B = i + 9j, find their scalar product AxB.
(Ans- AxB=33
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