1.the girl on the sled, weighing 50 lb, leaves point A from rest and goes down a 2% icy slope
no friction). She collides with her friend, weighing 60 lb, at
point B, 140 feet down the
slope. After colliding, they travel together down the slope on the sled. The slope is maintained, but the ice is a
little rougher, with a coefficient of friction of μk = 0.20.
a) How fast will they be moving immediately after they collide?
b) Will they come to a stop after the collision? If so, how far will they travel
until they do? If not, what will their acceleration be?
2.Q1) (15 points) In the diagram below, M1 = 50 Kg, M2 = 20 Kg, mass and radius of the
g and 30 cm each, respectively. Both M1 and M2 rest on frictionless surfaces and the system starts from rest.
(a) Draw the fbd for each of M1, M2 and the pulley.
(b) Write the equations of motion for each of M1, M2 and the pulley.
(c) Calculate the linear acceleration of the two masses, as well as the angular acceleration of the pulley.
(d) Calculate the angular velocity of the pulley after M1 and M2 have been displaced linearly by 2 m.
Q2) (10 points) A basketball is thrown with an initial speed v0 of 10.8 m/s at 400 above horizontal, and it enters the hoop from above. The ball is released at 2.00 m above the ground. The hoop is 3.05 m above the ground and 10.0 m away from the player.
(a) Find the time at which the ball passes through the hoop.
(b) Find the ball’s velocity (express in component form) just when it enters the hoop.
(c) Find the ball’s maximum height.
Q3) (5 Points) An object is thrown up from the top of a building of height of 400 m with an initial velocity of 20 m/s.
(a) Find the position and the velocity of the object 5 s later.
(b) With what velocity will it hit the ground?
(c) At the same time the first object is thrown up, a second object is thrown up from the ground at 100 m/s. Will the two objects collide? If yes, calculate when and where,
4.2)Two books are accelerating to the right on a frictional surface and the coefficient of kinetic friction between the floor
ction between the floor and book is µk. Using the information given in the figure:
(a) draw free body diagrams for both the books, and also for the combined system (of mass m1+m2),
(b) find acceleration of the books along horizontal direction, and
(c) find the magnitude and direction of the force exerted by the left book on the right book.
3.A car of mass 1500-kg enters a circular path at point P and leaves at point Q (see the figure) at constant speed of 5.0m/s, and the frictional force acting on its tires is 2500-N.
a) how long it takes to reach point Q from point P, and
b) what should be the minimum value of the coefficient of static friction between the tires and the road?
4)In an elevator which is accelerating downward at 2.5ms−2 , a 25-kg block hangs from a spring attached to the ceiling of the elevator. If spring gets stretched by 0.15m, find its spring constant.
5.Let's Play Ice Hockey!
An ice hockey player uses hockey stick to apply force on a motionless puck as shown on
motionless puck as shown on the picture above. The net force that the stick applies on the puck is 150N and the contact lasts for 7.5 ms. The mass of the puck is 166 g.
A) (1 point) Calculate the acceleration of the puck under the influence of the net force.
B) (2 points) Calculate the puck's change in momentum due to the impulse applied by the hockey stick.
C) (1 point) What is the velocity of the puck once it leaves the stick?
Puck travels over rough ice and comes to a stop after 25 m. The force diagram below shows all forces acting on the puck during that travel.
Screen Shot 2020-11-02 at 2.04.05 PM.png
D) (1 point) Calculate the work done on the puck by gravitational force.
E) (1 point) Calculate the work done on the puck by normal force.
F) (2 points) Calculate work done by friction force on the puck.
Now stationary, the puck (red) collides with a blue puck of the mass .332 kg moving to the left with velocity of 2.5 m/s. If collision is perfectly elastic calculate:
H) (2 points) Total momentum of blue+red puck system before collision?
I) (1 point) What is the total momentum of blue+red puck system after collision? How do you know?
J) (2 points) What is the velocity of the blue puck after collision?
9.1. A ball is thrown with an initial speed of 20 m/s at an angle of 60° to the ground.
ance is negligible, what is the ball’s speed at the instant it reaches its maximum height from the ground?
A. - 20 m/s
B. 0 m/s
C. + 17.3 m/s
D. + 10 m/s
E. + 20 m/s
2. A rhino charges full speed at a car with an initial velocity of 15 m/s. When the rhino collides with the car, it crumples in by 1 m before the rhino comes to a complete stop. What acceleration did the rhino feel as it came to a stop?
A. - 112.5 m/s^2
B. - 7.5 m/s^2
C. - 30 m/s^2
D. + 112.5 m/s^2
E. + 30 m/s^2
F. + 7.5 m/s^2
3. Two students want to determine the speed at which a ball is released when thrown vertically upward into the air. One student throws the ball into the air while the other student measures the total time that the ball is in the air. The students use a meterstick to measure the release height of the ball. Which of the following equations should the students use to determine the speed at which the ball was released? *
A. Use y final = y initial+ v initial *t + (1/2)*a*t^2 from the moment in time in which the ball was released to the moment in time in which the ball reaches its highest point.
B. v final^2 = v initial ^2 + 2a(????y) from the moment in time in which the ball was released to the moment in time in which the ball hits the ground.
C. Use y final = y initial+ v initial *t + (1/2)*a*t^2 from the moment in time in which the ball was released to the moment in time in which the ball hits the ground.
D. v final^2 = v initial ^2 + 2a(????y) from the moment in time in which the ball was released to the moment in time in which the ball reaches its highest point.
10.Use g = 9.8 m/s2.
The diagram below is a top-down view of two children pulling a 11.8-kg sled along the
ng the snow. The first child exerts a force of F1 = 11 N at an angle θ1 = 45° counterclockwise from the positive x direction. The second child exerts a force of F2 = 6 N at an angle θ2 = 30° clockwise from the positive x direction.
Find the magnitude (in N) and direction of the friction force acting on the sled if it moves with constant velocity.
direction (counterclockwise from the +x-axis)
What is the coefficient of kinetic friction between the sled and the ground?
What is the magnitude of the acceleration (in m/s2) of the sled if F1 is doubled and F2 is halved in magnitude?
12.I was wondering if you could help me with some Linear Motion Physics Problems. For the first question, I completed
n, I completed parts A and B, but can't get C. We get all the answers to the questions but not how to get to the answer. The question is:
Patrick changes velocity from 2.0 m/s North to 4.0 m/s South with an acceleration of 0.50 m/s/s South. (A) Determine how much time this process takes (ANSWER: 12 s). (B) Find his displacement (magnitude and direction) (ANSWER: 12 m South). (C) Find how much distance Patrick covered (ANSWER: 20 m).
Another question I was having trouble with was this (I got part A but not parts B or C):
Two cars are traveling along a straight line in the same direction, the lead car at 25.0 m/s and the other car at 30.0 m/s. At the moment the cars are 40.0 m apart, the lead driver applies the brakes, causing his car to have an acceleration of -2.00 m/s/s. (A) How long does it take for the lead car to stop? (ANSWER: 12.5 s). (B) Assuming that the chasing car brakes at the same time as the lead car, what must be the chasing car's minimum negative acceleration so as not to hit the lead car? (ANSWER: -2.29 m/s/s). (C) How long does it take for the chasing car to stop? (ANSWER: 13.1 s).