1) In the figure, a crate with mass M is on a rough surface inclined at 30°. A c
ID: 1785794 • Letter: 1
Question
1) In the figure, a crate with mass M is on a rough surface inclined at 30°. A constant external force is applied horizontally to the crate. As the force pushes the crate a distance of up the incline, the speed changes from 1.40 m/s to 2.50 m/s. If the magnitude of the work done by gravity on the crate during this process is 10,300J, What is the mass of the crate and the sign of the work done by gravity?
A) 700kg, Negative
B) 400 kg, Positive
C) 700 kg, Positive
D) 340 kg, Negative
E) 800kg, Negative
Answer: A
2) A mass is pressed against (but is not attached to) an ideal horizontal spring on a frictionless horizontal surface. After being released from rest, the mass acquires a maximum speed v and a maximum kinetic energy K. If instead the mass initially compresses the spring half as far,
A) its maximum speed will be 2v and its maximum kinetic energy will be 2K.
B) its maximum speed will be v and its maximum kinetic energy will be K/.
C) its maximum speed will be v/ and its maximum kinetic energy will be K/2.
D) its maximum speed will be v/2 and its maximum kinetic energy will be K/4.
E) its maximum speed will be 4v and its maximum kinetic energy will be 2K.
Answer: C
3) In the figure, a 5.00-kg block is moving at 5.00 m/s along a horizontal frictionless surface toward an ideal massless spring that is attached to a wall. After the block collides with the spring, the spring is compressed a maximum distance X, measured in meters. Knowing that the speed of the block when it has moved so that the spring is compressed to only one-half of the maximum distance is equal to 4.3 m/s, what is the value for X?
0.68m
0.78m
0.98m
6.8m
0.068m
Answer: A
4) A stationary object is struck by a stick. The object experiences a horizontal force given by F = at - bt2, where t is the time in milliseconds from the instant the stick first contacts the object. If a = 1500 N/(ms) and b = 20 N/(ms)2 , The speed of the object just after it comes away from the stick at t = 2.74 ms, is 3.3m/s. What is the mass of the object?
A) 1.67-kg
B) 16.7-kg
C) 167-kg
D) 0.167-kg
Answer: A
5) A 310-g air track cart is traveling at 1.25 m/s and a 260-g cart traveling in the opposite direction at a constant speed V. If the speed of the center of mass of the two carts is 0.0732m/s. What is the speed of the 260-g cart??
A) 1.80 m/s
B) 1.33 m/s
C) 0.133 m/s
D) 1.47 m/s
E) 1.29 m/s
Answer: B
6) Three objects are connected by massless wires over a massless frictionless pulley as shown in the figure. The tension in the wire connecting the 10.0-kg and 15.0-kg objects is measured to be 133 N. What is the mass M?
A) 8.33 kg
B) 33.9 kg
C) 35.0 kg
D) 52.8 kg
E) 95.0 kg
Answer: D
7) In the figure, point P is at rest when it is on the x-axis. The time t, when P returns to the original position on the x-axis, is closest to
A) 13 s.
B) 18 s.
C) 25 s.
D) 35 s.
E) 50 s.
Answer: D
I have the answer for each one of them. Please show me how to work it .
Explanation / Answer
6) Let tension of the 133N wire: T_2
First, we need to find the acceleration of the 10kg block, which is also the acceleration of the entire system.
T_1 - m*g = ma
(T_1 - m*g) / m = a
(133N - (10kg * 9.8 m/s^2)) / 10kg = 3.5 m/s^2
Now, find the tension of the longer wire using the 15kg block.
F_y = T_1 - m*g - T_2 = m*a
T_1 = m*a + m*g +T_2
T_1 = (15kg)(3.5m/s^2)+(15kg)(9.8m/s^2) + 133N
T_1 = 332.5N
Now, add the forces in the y direction for the block of mass unknown.
F_y = T_1 - m*g = -m*a (accelerating downward)
T_1 = -m*a + m*g
T_1 = m(g - a)
m = T_1 / (g - a)
m = 332.5N / (9.8m/s^2 - 3.5m/s^2)
m = 52.8kg
Related Questions
Navigate
Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.