Question

1. A ball rolls across a floor with an acceleration of 0.10 m/s² in a direction opposite to its velocity. The ball has a velocity of 4.00 m/s after rolling a distance 6.00 m across the floor. What was the initial speed of the ball?

A) 4.15 m/s

B) 5.85 m/s

C) 4.60 m/s

D) 5.21 m/s

E) 3.85 m/s

2. A string is wrapped around a pulley with a radius of 2.0 cm. The pulley is initially at rest. A constant force of 50 N is applied to the string, causing the pulley to rotate and the string to unwind. If the string unwinds 1.2 m in 4.9 s, what is the moment of inertia of the pulley?

A) 0.17 kg∙m²

B) 17 kg∙m²

C) 14 kg∙m²

D) 0.20 kg∙m²

E) 0.017 kg∙m²

3. A soccer ball (mass = 0.43 kg) is moving at a speed of 20 m/s when it is kicked with a force of 300 N resulting in it going in the opposite direction with the same speed as before. What is the magnitude of the impulse delivered to the ball?

A)	0, because the before and after momenta cancel each other.
B)	8.6 kg·m/s
C)	17 kg·m/s
D) E)	2600 kg·m/s 6000 kg·m/s

4. A force F = 4.00 N i - 3.00 N j is applied to an object at position r = 2.00 m i   + 3.00 m j . What is the torque about the origin?

A) 8.00 N∙m i - 9.00 N∙m j  

B) -1.00 N∙m k  

C) 8.00 N∙m i + 9.00 N∙m j  

D) 17.0 N∙m   k

E) -18.0 N∙m   k

5. A 3.00-m long plank of negligible mass has a 30.0-kg mass at one end and a 40.0-kg mass at the other end. How far from the 30.0-kg mass should a fulcrum be placed so that the plank is balanced?

A) 1.71 m

B) 1.29 m

C) 0.750 m

D) 1.50 m

E) 2.25 m

6. An 8 kg object moving with an initial velocity of 4 m/s comes to rest due to friction after it travels a horizontal distance of 10 m. If the initial speed of the object is doubled, what distance will it travel before coming to rest? Use g = 10 m/s2.

A) 10 m

B) 20 m

C) 30 m

D) 40 m

E) 80 m

7. A 0.500-kg object rests on a horizontal frictionless surface. It is in a position such that it is compressing a spring a distance 12.0 cm. If the object is released, the object leaves the spring at a speed of 20.0 cm/s. What is the spring constant of the spring?

A) 2.78 N/m

B) 2.19 N/m

C) 3.17 N/m

D) 1.39 N/m

E) 0.333 N/m

8. A person applies a constant force on an object of mass 20 kg that causes the object to move horizontally at a constant speed of 0.20 m/s through a distance of 0.80 m. What is the work done on the object?

A) 160 J

B) 10 J

C) 16 J

D) 0 J

E) Cannot be determined without knowing the magnitude of the applied force.

9. A packing crate slides down an inclined ramp at constant velocity. Thus we can deduce that

A) a frictional force is acting on it.

B) a net downward force is acting on it.

C) a net upward force is acting on it.

D) it is not acted on by appreciable normal force.

E) it is not acted on by appreciable gravitational force.

10. An object has a position given by r = [2.0 m + ( 3.00 m/s)t]   + [3.0 m - ( 2.00 m/s²)t²] . What is the speed of the object at time t = 2.00 s?

A) 5.00 m/s

B) 8.54 m/s

C) 5.50 m/s

D) 4.65 m/s

E) 11.0 m/s

Answer 1

1)

v = 4m/s ,a = (- 0.1m/s² )

s = 6m, u = ?

substituing the above values,

u² = 17.2

u = 4.147 m/s

ans is option (a) 4.15m/s

3) Mass, m = 0.43 kg

Speed, v = 20 m/s

Force, F = 300 N

FΔt = mΔv

Impulse = change in momentum

momentum of the soccer ball = mass × velocity

= 0.43 kg × 20 m/s

                                                       = 8.6 kgm/s

answer is option (b)

4)

   ans is option (e)

8) Ans is 0 J because change in kinetic energy is zero

9) Ans is (a)

10)

ans is option (b)