Force Fundamentals
Systems
Uphill Battles
Round and Round
Wildcard
100
A ball moves horizontally with an initial velocity v0, as shown above. It is then struck by a tennis racket. After leaving the racket, the ball moves with a velocity v. Which of the following vectors best represents the direction of the average force that the racket exerts on the ball?
D
100
A force F accelerates a system of two blocks X and Y on a horizontal frictionless surface as shown. The acceleration is 4 m/s/s. The force with which block Y pushes on block X has a magnitude
(A) 0N (B) 6N (C) 8N (D) 16N (E) 24 N
(D) 16N
100
A 3kg block slides down a 30o ramp at a constant velocity. What is the magnitude of the frictional force acting on it?
14.7 N
mg*sin(theta)=Ff
100
A ball on the end of a string is swung in a vertical circle. The mass of the ball is 0.25 kg and the radius of the
circle is 0.75 m. When at IV, the tension in the string is twice as great as the weight of the ball. Determine the speed of the ball at IV.
3.9 m/s
Fg=2.5 FT=FC
5=mv2/r
100
9. A large 50-kg dog stands on a scale in an elevator that is moving downward, but slowing with an acceleration of magnitude 2.0 m/s2. What does the scale read (in N)?
590 N
200
If the coefficient of friction between the object and the horizontal surface is 0.25, what will be the acceleration of the object?
7.9 m/s2
200
A block of mass 3m can move without friction on a horizontal table. If the masses of the cord and the pulley are negligible, what is the magnitude of the acceleration of the descending block?
g/4
200
A 4 kg block slides up a 25° incline with an initial speed of 6 m/s. The coefficient of kinetic friction is 0.20. How far up the incline does it travel before coming to rest?
3.05m
200
The "Rotor" ride is the one that presses you against the walls of the spinning rotor as the floor drops away. The coefficient of static friction between the wall and a rider is μ = 0.06. If the ride is rotating at an angular velocity of 5.2 rad/s, what must be the radius of the rotor?
6.05m
200
A student pulls a wooden box along a rough horizontal floor at constant speed by means
of a force P as shown to the right. Which of the following must be true?
(A)
300
A block is given an initial velocity vo when it is at the bottom of a rough inclined plane. Which of the following is true about the block's acceleration as it moves up/down the plane?
(A) a UP = a DOWN
(B) a UP > a DOWN
(C) a UP < a DOWN
(D) It has a varying acceleration as it moves up and down the plane.
(B) a UP > a DOWN
300
Calculate the acceleration of the blocks if the coefficient of kinetic friction between the m2 block and the table is 0.35.
m1 = 4kg, m2 = 1kg, and m3 = 2kg.
2.31 m/s2
300
A 5kg block is on a frictionless ramp, at an angle of 60 ° above the horizontal. A 4kg block hangs from a pulley over the edge (straight down). What is the tension in the string?
40.64 N
a=-0.36m/s2
300
A highway curve that has a radius of 100m is banked 15°. A car successfully negotiates the curve at 25 m/s. Determine the minimum value of the coefficient of friction necessary to keep this car from sliding as it goes around the curve.
0.316
300
A 2 kg block is pushed against a vertical wall with 40 N of force. The coefficient of static friction is 0.4. Will it stay up? Explain breifly
No, Ffs_max (16N) < Fg (19.6)