Physics 201 MWF10:20 Fall 1995 (Ford)
Exam I Chapts. 1-5 in SZY College Physics

THE ANSWERS ARE WRITTEN IN THE BLANKS. PLEASE LET ME KNOW (EMAIL OR PHONE) IF YOU THINK AN ANSWER IS INCORRECT!!!!


(16 pts) 1. Vectors A and B are given in the sketch.

a) What are the x and y components of the vector A?

Ans. A_x = __-3.61 m__

A_y = __+4.79 m__

b) What are the magnitude and direction (angle ) measured counterclockwise from the +x-axis) of the vector C that is the sum of the vectors A and B shown in the sketch (C = A + B)?

Ans. C =__3.44 m__

= __107^o__


(20 pts) 2. A small rock is thrown straight up from the roof of a building. The rock has an initial speed of v₀ = 15 m/s. The rock strikes the ground 6.0 s after being thrown.

a) What is the magnitude of the velocity of the rock when it is at its maximum height above the roof?

Ans. __0__

b) What is the acceleration (magnitude and direction) of the rock when it is at its maximum height above the roof?

Ans. a = __9.8 m/s²__

direction = __downward__

c) What is the height of the building?

Ans. __86.4 m__


(21 pts) 3. A small cube of ice slides off a horizontal tabletop with an initial velocity that is horizontal and has magnitude 8.0 m/s as leaves the tabletop. The tabletop is a vertical distance of 4.9 m above the floor.

a) How much time does it take for the ice cube to reach the floor?

Ans. __1.0 s__

b) What is the horizontal distance from the edge of the tabletop to the point where the ice cube hits the floor.

Ans. __8.0 m__

c) What are the horizontal and vertical components of the velocity of the ice cube just before it strikes the floor?

Ans. horizontal = __8.0 m/s; to right__

vertical = __-9.8 m/s; downward__


(21 pts) 4. A block with mass m = 2 kg is released at the top of an inclined plane that has slope angle = 37°. The block has an acceleration of a = 5.0 m/s² as it slides down the incline.

a) What is the normal force exerted by the incline on the block as it slides down?

Ans. __15.7 N__

b) What is the friction force exerted by the incline on the block as it slides down?

Ans. __1.8 N__

c) What is the coefficeint of kinetic friction µ_k between the block and the incline?

Ans. __0.114__

(22 pts) 5. A 4.0 kg block on a horizontal tabletop is connected by a massless rope that passes over a massless, frictionless pulley to a hanging block of mass m. The coefficient of kinetic friction between the 4.0 kg block and the tabletop is µ_k = 0.2. When the blocks are released, the hanging block descends with an acceleration of 3.0 m/s².

a) While the blocks are moving, what is the magnitude of the friction force on the 4.0 kg block?

Ans. __7.84 N__

b) While the blocks are moving, what is the tension in the rope that connects the two blocks?

Ans. __19.8 N__

c) What is the mass m of the hanging block?

Ans. __2.91 kg__