i could use some help with these problems... 1)1)Check the boxes beside the stat
ID: 1278441 • Letter: I
Question
i could use some help with these problems...
1)1)Check the boxes beside the statements that are TRUE, regarding force and motion.
Select all that are True.
If there is a net force acting on an object, the object's velocity will change.
If an object has a constant speed, the net force acting on it must be zero.
If an object has a constant velocity, the net force acting on it must be zero.
If an object at rest remains at rest, the net force acting on it must be zero.
To keep an object moving at a constant velocity, a small net force is required to prevent it from slowing down.
If two different objects are under the influence of equal forces, they will have equal accelerations.
The net force on a moving object is suddenly reduced to zero. What happens as a result of this?
The object's velocity changes in an unpredictable way.
The object gradually slows down to a stop.
The object continues moving with a constant velocity.
The object immediately stops.
The object's velocity changes direction.
3)An astronaut on the moon momentarily holds a stone weighing 5 N in his hand. He then throws it upward. What is the net force (magnitude and direction) on the stone while he is holding it? What is the net force on the stone shortly after it leaves his hand?
5 N upward; 5 N downward.
Zero; 5 N downward.
Zero; 5 N upward.
5 N upward; zero.
Zero; zero.
4)Consider a human who weighs 684 N on Earth. What is the person's mass on Earth?
What is the same person's mass on Mars, where the acceleration due to gravity is 3.7 m/s2?
5)Two books of mass m1 = 3.3 kg and m2 = 5.6 kg are stacked on a table as shown in Figure Q3.16. Find the normal force acting between the table and the book on the bottom.
6)Imagine a landing craft approaching the surface of Callisto, one of Jupiter's moons. If the engine provides an upward force (thrust) of 3096 N, the craft descends at constant speed; if the engine provides only 2090 N, the craft accelerates downward at 0.39 m/s2. What is the weight of the landing craft in the vicinity of Callisto's surface?
b. What is the mass of the craft?
c. What is the magnitude of the free-fall acceleration near the surface of Callisto?
7)A 1.65 kg mass is suspended from a string which is pulled upward. The mass accelerates upwards with an acceleration of 2.70 m/s2. What is the tension in the string?
8)A 11.2-kg block is suspended from the ceiling of an elevator by a cord rated to withstand a tension of 166 N. Shortly after the elevator starts to ascend, the cord breaks. What was the minimum acceleration of the elevator when the cord broke?
9)Three blocks on a frictionless surface are connected by massless strings, with M1 = 1.80 kg, M2 = 2.00 kg, and M3 = 3.80 kg. Due to the force F acting on M3, as shown, the system accelerates to the right. Given that T1 is 3.30 N, calculate T2
10)Two blocks are in contact on a frictionless table. A horizontal force F is applied to m1, as shown. If m1 = 1.54 kg, m2 = 3.70 kg, and F = 5.20 N, find the magnitude of the force between the two blocks.
Explanation / Answer
1) as F=ma and a= dv/dt true statements are
If there is a net force acting on an object, the object's velocity will change
If an object has a constant velocity, the net force acting on it must be zero
If an object at rest remains at rest, the net force acting on it must be zero
2) explanation same as above.
ans: The object continues moving with a constant velocity
3) when the stone is in astranauts hands no accereation is there as gravitational force is balanced by normal contact froce from hand .
hence force is zero.
after it leaves hand net force =5N downwards hence
b) correct option.
4) W=mg
m=W/g= 684 N/9.81m/sec2= 69.72 Kg
mass does not depend upon gravity mass will be same on mars as on earth.
5) N=(m1+m2)g= 8.9x9.8 N=87.22N
6) a) from given information Weight of spacecraft on callisto surface W= 3096N
b) from second information we can write that
W-2090= ma
a=0.39m/sec2
thus m=(3096-2090)/0.39 Kg =2579.48 Kgs
c ) W=mg
g=W/m= 3096N/2579.48Kg= 1.2m/sec2
7) T-Mg=Ma
T=M(g+a) =1.65(9.81+2.70)=20.64N
8) T=M(g+a)= 11.2(9.8+a)
for cable to braek minimum tension is 166N
thus 166=11.2(9.8+a)
a=5.02m/sec2
9) writing newtons equation for both boxes
for 1
5.2-T=1.54a...(1)
for block 2
T=3.70a....(2)
solving (1)and (2)
T=3.67N
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