ADVERTISEMENT

Form D

Exam 2 PHY231 Spring 2013 Section 2

1. A 2.00-kg projectile is fired upward at an angle of 20.0°. What is the magnitude of the force

exerted on the projectile when it is at the highest position in its trajectory? Neglect any effects of

air resistance.

A) 6.24 N

E) 0.34 N

F = mg (downward), throughout motion

B) 10.4 N

F) 9.81 N

F = (2.00kg)(9.81 N/kg) = 19.6 N

C) 15.8 N

G) 19.6 N

D) 0.68 N

H) 0.00 N

2. Two forces act on a 4.5-kg block resting on a

frictionless surface as shown. What is the magnitude

= ma

F

of the horizontal acceleration of the block?

x

x

(

)

2

2

A) 1.78 m/s

E) 2.04 m/s

3.7 + 5.9cos 43°

N

F

x

=

=

= 1.78m/s

2

2

a

B) 1.22 m/s

F) 0.82 m/s

x

m

4.5kg

2

2

C) 1.05 m/s

G) 8.90 m/s

2

2

D) 1.95 m/s

H) 3.20 m/s

3. A 4.00 kg block is connected by means of a mass-less rope to a 2.00 kg

block as shown in the figure. Complete the following statement: If the

4.00 kg block is to begin sliding, the coefficient of static friction between

the 4.00 kg block and the surface must be

A) less than zero

E) Less than 1.00 but greater than 0.75

B) greater than 2.00

F) Less than 0.75 but greater than 0.50

C) less than 2.00 but greater than 1.50

G) Less than 0.50 but greater than 0.00

D) less than 1.50 but greater than 1.00

H) Need more information to answer the question.

4. A rock is suspended from a string and moves downward at constant speed. Which statement is

true concerning the string tension if air resistance is ignored?

A) The string tension has a magnitude of zero newtons.

B) The string tension acts downward on the rock

C) The string tension is equal to the weight of the rock

D) The string tension is twice the weight of the rock

E) The string tension is half the weight of the rock

F) The string tension is only slightly less than the weight of the rock

G) The string tension is only slightly greater than the weight of the rock

H) The string tension starts less than, but becomes greater than the weight of the rock

5. A concrete block is pulled 7.00 m across a

frictionless surface by means of a rope. The

rope tension is 40.0 N; and the net work done

on the block is 247 J. What angle does the

rope make with the horizontal?

Δx = T (cos θ )Δx

W = F

A) 28.1°

E) 50.1°

x

(

)

(

)

B) 35.1°

F) 53.1°

θ = cos

−1

−1

⎡ ⎣

⎤ ⎦

W T Δx

= cos

247 (40)(7)

C) 43.1°

G) 57.1°

D) 47.1°

H) 88.1°

= 28.1°

1

ADVERTISEMENT

0 votes

Parent category: Education