PHY 201/211 General Physics

PHY 201/211 General Physics Odd Sections. 9:30-10:20 lecture Test III

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Answer all problems.

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formula sheets are also provided at the back of this test.

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Problem No.	Score
1
2
3
4
Total

1. (25points)

Circle the right answers. Only one choice is correct. No penalty for wrong guess.

I. A cart on a frictionless track is released from rest at point P. At which of the following points the block is moving the fastest? Assume the cart stays on the track all the time.

A. A

B. B

C. C

D. D

E. E

II. Two objects make a completely inelastic collision, which statement is not correct?

A. Momentum is conserved by the collision.

B. The two objects stick together after the collision.

C. Mechanical energy is conserved by the collision.

D. Center of mass of the two objects moves with a constant velocity during the collision.

E. The two objects exert equal and opposite forces on each other during the collision.

III. Unit of gravitational constant G is

A. Kg²m^-2

B. Nm²Kg^-2

C. N

D. Kg^-2m²

E. No unit.

IV. A racing car running on a circular track requires a frictional force F to maintain the circular motion. If its speed is doubled, the required frictional force will be

A. 0.5F

B. 0.25F

C. 2F

D. 4F

E. None of above.

V. A 800 kg tractor is moving up a slope at a uniform rate. It climbs a height of 15m in 5s. What is the power of the engine?

A. 2.35x10⁴ W

B. 1.18x10⁵ W

C. 1.57 kW

D. 7.84 kW

E. No enough information.

2. (25 points)

A gun is fired vertically into a 1kg block of wood at rest directly above it. If the bullet has a mss of 25.0g and a speed of 250 m/s, how high will the block rise into the air after the bullet becomes embedded in it?

3. A roller coaster is released from rest at a certain height. It runs through a vertical loop of 25m in radius. There is no friction until break is applied at the horizontal section.

a. (5 points)

What is the normal force acting from the seat on the passenger when the passenger starts to fall out from the cart?

b. (10 points)

What is the minimum speed of the cart at the highest point of the loop to prevent the passenger from falling out?

c. (10 points)

If the speed of the roller coaster at the highest point of the loop is 20 m/s. When the break is applied, coefficient of kinetic friction at the horizontal section is 0.75. What is the distance traveled by the roller coaster before it comes to a complete stop?

4. Ball A (4kg in mass) is moving towards right with a velocity of 3.33 m/s and collides with ball B (1kg in mass). Ball B is at rest before the collision.

(a) (15 points)

If ball A moves in the original direction (i.e. towards right) with a velocity of 2.33 m/s after the collision, what is the velocity of ball B after the collision?