Basic Physics I

Exam I Spring 2007

1.         A vector has components A_x = -8m and A_y = -6m.  Find the magnitude of the vector and the angle, q, it makes with the positive x axis.  Sketch the vector in your bluebook.

2.     A ball is thrown with a speed of 30m/s at an angle of 30^o above the horizontal.  What is the maximum elevation, or height, it will reach?  (Assume it starts at the surface of the earth.)

3.     A car is moving to the right with a speed of 30m/s.  It experiences an acceleration of 4m/s² to the left.  How long will it take to slow to a speed of 10m/s?

 

A.     A box of mass M starts from rest on top of a frictionless incline of angle q.  It takes 4 seconds for the box to slide to the bottom, a distance of 12m.  Draw a free body diagram showing all the forces and find the angle q?  Neglect friction. 

 

 

 

B.     I am pulling a 22kg sled along a level sidewalk with a constant velocity.  I exert a force of P at and angle of 37^o above the horizontal.  The coefficient of friction is 0.5.  Draw a free body diagram showing all the forces and find the magnitude of the force P. 

 

 

 

C.     The mass M is suspended by two strings as shown at the right.  If the tension T₁ = 100N, find the mass M.  Draw a free body diagram showing all the forces.

 

 

 

 

 

 

 

Formulae and Expressions.

 

In the figure at the right, B = C cos(J),  A = C sin(J), tan(J) = A/B, and     A² + B² = C².

 

 

Implies A_x +B_x = C_x and A_y + B_y = C_y. 

 

In the figure at the right A_x = |A|cos(J) and A_y = |A|sin(J). 

 

 

 

f_static £ m_sF_N               f_kinetic = m_kF_N              a_R= v²/R