PHYS231 - Exam 1

A pilot drops a package from a plane flying horizontally at a constant speed. Neglecting air resistance, when the package hits the ground the horizontal location of the plane will A. be in front of the package B. be directly over the package C. depends on the speed of the plane when the package was released D. be behind the package

B. be directly over the package

A boy jumps with a velocity of magnitude 20.0 m/s at an angle of 25 degrees above the horizontal. What is the horizontal component of the boy's velocity? A. 18.1 m/s B. 8.45 m/s C. 9.33 m/s D. 12.6 m/s E. 15.6 m/s

A. 18.1 m/s

Rank in order, from the most to the least, number of sig figs in the following numbers. a. 8200 b. 0.0052 c. 0.430 d.4.321X10^-10 A. d>c>b=a B. a=b=d>c C. b=d>c>a D. d>c>a>b

A. d>c>b=a

Suppose that an object is moving with constant velocity. Which statement concerning its acceleration must be correct? A. the acceleration is equal to zero B. the acceleration is constantly decreasing C. the acceleration is a constant non-zero value D. the acceleration is constantly increasing

A. the acceleration is equal to zero

At the turning point of an object, A. the instantaneous velocity is zero B. the acceleration is zero C. both A snd B are correct D. neither A nor B is true

A. the instantaneous velocity is zero

For general projectile motion with no air resistance, the vertical component of a projectile's acceleration A. continuously decreases B. remains a non-constant zero C. first decreases and then increases D. continuously increases E. is always zero

B. remains a non-constant zero

A small car and a large SUV are at a stoplight. The car has a mass equal to half of that of the SUV, and the SUV can produce a maximum accelerating force equal to twice that of the car. When the light turns green, both drivers push their accelerators to the floor at the same time. Which vehicle pulls ahead of the other vehicle after a few seconds? A. the SUV pulls ahead B. the car pulls ahead C. it is a tie

B. the car pulls ahead

A water rocket can reach a speed of 75 m/s in 0.050 seconds from launch. What is its average acceleration? A. 700 m/s2 B. 750 m/s2 C. 1500 m/s2 D. 2250 m/s2 E. 3000 m/s2

C. 1500 m/s2

A person using a rope to lower a 5 N bucket into a well with a constant speed of 2.0 m/s. What is the magnitude of the force exerted by the rope on the bucket? A. 49 N B. 2.0 N C. 5.0 N D. 0.0 N E. 10 N

C. 5.0 N

When a ball is thrown straight up with no air resistance, the acceleration at its highest point A. is zero B. reverses from downward to upward C. is downward D. is upward

C. is downward

Suppose that an object travels from one point in space to another. Make a comparison between magnitude of the displacement and the distance travelled by this object. A. the displacement can be either greater than, smaller than, or equal to the distance travelled B. the displacement is either greater than or equal to the distance travelled C. the displacement is either less than or equal to the distance travelled D. the displacement is always equal to the distance travelled

C. the displacement is either less than or equal to the distance travelled

The slope at a point on a velocity v. time graph of an object is A. the objects speed at that point B. the objects average velocity at that point C. the objects instantaneous velocity at that point D. the objects acceleration at that point E. the distance travelled by the object at that point

C. the objects instantaneous velocity at that point

A heavy red ball is released from rest at 2.0 m above a flat, horizontal surface. At exactly he same instant, a yellow ball with the same mass is fired horizontally at 3.0 m/s. Which ball hits the ground first? A. the red ball hits first B. the yellow ball hits first C. they hit at the same time

C. they hit at the same time

Projectiles 1 and 2 are launched over level ground with different speeds. Both reach the same height. Which hits the ground first? A. projectile 1 B. projectile 2 C. they hit the ground at the same time

C. they hit the ground at the same time

How many significant figures does 23.21 have? A. 2 B. 1 C. 3 D. 4 E. 5

D. 4

A motorist travels 160 km/h and 160 km/h. What is the average speed of the motorist for the trip? A. 91 km/h B. 848 km/h C. 90 km/h D. 89 km/h

D. 89 km/h

The area under a velocity v. time graph of an object is A. the objects speed at that point B. the objects acceleration at that point C. the distance travelled by the object D. the displacement of the object

D. the displacement of the object

For general projectile motion with no air resistance, the horizontal component of a projectile's acceleration A. continuously decreases B. remains a non-constant zero C. first decreases and then increases D. continuously increases E. is always zero

E. is always zero

You push on box G that is next to box H, causing both boxes to slide along the floor. The reaction force to your push is A. the push of box G on box H B. the upward force of the floor on box G C. the push of box H on box G D. the acceleration of box G E. the push of box G against you

E. the push of box G against you

True or False. If the velocity of an object is zero at some point, the acceleration must also be zero at that point.

False

True or false. If the acceleration of an object is zero, then that object cannot be moving.

False