Physics 1010Exam #1 reviewGeneral Test Information 7:30 tonight in this room (G1B20). Closed book. Single 3x5 note card with own notes writtenon it allowed. Calculators are allowed (no memory usage). Worth 40 points total. Multiple choice plus one long hand question.Concept Overview Kinematics - velocity, acceleration, etc. Dynamics – Newton’s laws Forces of interest – gravity, friction, andsprings If you are comfortable with these concepts,you can handle any problem on the test!Velocity Velocity is the changeof an object’s positionwith respect to time. x is position, v isvelocity.txv!!=01234567890 s 1 s 2 s 3 s 4 sTimePositionVelocity is the slope!Acceleration Acceleration is the changeof an object’s velocity withrespect to time. v is velocity, a isacceleration.tva!!=00.511.522.50 s 1 s 2 s 3 s 4 sTimeVelocityAcceleration is the slope!Kinematic Equations of Motion Velocity as a function of time:Similarly for position:v = v0 + atx = x0 + v0t + (1/2) at2Newton’s Second Law Fundamental equation of dynamics:F = m a A quantitative generalization of Newton’sfirst law. Acceleration is in the same direction as netforce.Newton’s First Law An object that is not subject to any outsideforces moves at a constant velocity. When an object is not accelerating, it can stillbe subject to external forces, but the net forcevanishes. In the object’s frame of reference, there’s noway to distinguish uniform motion fromsitting still.Newton’s Third Law For every force that one objects exerts on asecond object, there is an equal and oppositeforce that the second object exerts on the first. This does not apply to two forces acting onthe same object.Gravity Objects of different masses fall at the samerate. The gravitational force on an object must beproportional to its mass.2/ 8.9 smgmgFgravity!=Friction Frictional forces oppose motion. Two types: static and sliding. Sliding friction force is generally smallerthan weight force. Friction forces on an object are related to theweight force on the object.Springs Hooke’s law:kxFspring!= The spring force is a restoring forceproportional to the displacement of theobject. Spring constant k depends on the type ofspring.Clicker Question 1At t=0 s, a 0.5 kg ball is thrown straight up with an initialvelocity of 20 m/s. At what time will it reach its maximumheight?A. 0.0 sB. 0.707 sC. 1.0 sD. 2.04 sAnswer: (+ is up) vf=vi+at vf=0, vi=20m/s, a=-9.8m/s2: D (+ is down) vf=vi+at vf=0, vi=-20m/s, a=9.8m/s2: DClicker Question 2A. 61.2 mB. 40.1 mC. 20.4 mD. 54.3 mAnswer: x=xi+vit+(1/2)at2 xi=0, vi=20m/s, a=-9.8m/s2, t=2.04s CAt t=0 s, a 0.5 kg ball is thrown straight up with an initialvelocity of 20 m/s. What is the maximum hight it reaches (+is up)?Clicker Question 3At t=0 s, a 0.5 kg ball is thrown straight up with an initialvelocity of 20 m/s. At what height is the ball when its velocityis half its initial value?A. 10.2 mB. 15.3 mC. 4.9 mD. 18.6 mAnswer: vf=vi+at vf=10m/s, vi=20m/s, a=-9.8m/s2, t=1.02s x=xi+vit+(1/2)at2 xi=0, vi=20m/s, a=-9.8m/s2, t=1.02sBKinematics Tips Pick a positive direction Make sure all your values have the correctsign If question is composite FIND TIME FIRSTClicker Question 4A woman hangs a 1 kg mass on the end of a spring with k =200 N/m. How far does the spring stretch from its positionbefore the mass was suspended? (disregard the sign)A. About 2 cm.B. About 5 cm.C. About 10 cm.D. With such a large spring constant, it would hardly move.Answer: mg=-kx, x=-mg/k=-0.049m=-4.9cm BClicker Question 5A. 9.8 m/s2.B. 0 m/s2.C. 8.9 m/s2.D. 0.89 m/s2.Answer: mg=(M+m)a, a=mg/(M+m) DF =mgM = 1 kgm = 0.1 kgA cart of mass of 1kg is attached to a hanging weight of mass0.1kg. They accelerate at:Clicker Question 6Answer: AYou are pushing a cart up a ramp. Which vector best represents:The direction of the force of gravity on the cart.Clicker Question 7Answer: DYou are pushing a cart up a ramp. Which vector best represents:The direction of the force the surface of the ramp exerts on the cart.Clicker Question 8Answer: EYou are pushing a cart up a ramp. Which vector best represents:The direction of the force of gravity and the force that the surface of the ramp exerts on the cart, added