Quiz 1.1

The normal force on an object always acts:

• perpendicular to the surface upon which the object is resting.

• parallel to the surface upon which the object is resting.

• equal and opposite to the weight of the object.

• in the same direction as gravity.

Frictional forces will always act in:

• the same direction the object is moving.

• a direction toward the Earth’s center.

• a direction perpendicular to the surface.

• the opposite direction the object is trying to move.

The box below is pulled along the floor with a force  $F$  , directed at an angle  $\theta$  above the horizontal. What is the horizontal component of the force  $F$  ?

•  $F\sin\theta$  

•  $F_g$  

•  $F\tan\theta$  

•  $F\cos\theta$  

A 16 kg book is held against the wall with a force directed horizontally into the wall. Which of the following shows the correct free-body diagram for this situation?

• 
• 
• 
• 

The picture below shows a box sliding down a rough incline at a constant speed. Which of the following is the correct free-body diagram?

• 
• 
• 
• 

A box is at placed on an inclined surface as shown. What is the magnitude of the normal force acting on the box?

• $F_g$

• $F_g\cos\theta$

• $F_g\sin\theta$

• $F_g\tan\theta$

A box of mass  $m$  is pushed across a frictionless surface with a force  $F$  . If the force is suddenly removed, the box:

• will speed up and then change directions. 

• will continue to move in a straight line at a constant speed. 

• will do something unpredictable. 

• will slow down and then speed up.

A box rests on a horizontal surface. A 142 N force is applied to the box. If the box is still at rest, what is the frictional force on the box?

• 142 N

• 490 N

• 196 N

• 2.8 N

A gravitational force of 392 N is acting on a person standing on the ground. How much normal force is acting on the person?

• 163 N

• 392 N

• 4 N

• 9.8 N

A force of 243,987,450.78 N is applied to an object 37° above the horizontal and 53° out of the page. Since this is the last question, which choice is the correct answer?

• nope

• seriously?

• close... go one more

• this one