Emily challenges her husband, David, to catch a $1 bill as follows. She holds the bill vertically as in Figure P2.67, with the center of the bill between David's index finger and thumb. David must catch the bill after Emily releases it without moving his hand downward. If his reaction time is 0.2 s, will he succeed? Explain your reasoning. (This challenge is a good trick you might want to try with your friends.) Figure P2.67

At a soccer practice, the players run sprints. They start at the goal, run 10 m toward the center of the field and then run back to the goal. Then they run 20 m toward the center of the field and back to the goal. Finally they run 30 m toward the center of the field, turn around, and run back to the goal again. One player times herself to try and beat her personal best time. She runs the first 10 m in 2.5 s and gets back to the goal in 2.8 s. Then she runs the 20-m sprint in 5.7 s and gets back to the goal in 6.7 s. She runs the final 30-m sprint in 12 s and gets back to the goal in 15 s. Define the positive direction as forward, toward the center of the field and consider what a position versus time graph of her motion would look like. Rank the sprints according to their slopes on the position versus time graph, from steepest positive slope to steepest negative slope. Rank from steepest positive slope to steepest negative slope. To rank items as equivalent, overlap them.

Q1.An electron, in a picture tube of a TV set, travelling in a straight line, accelerates uniformly from speed 4.3x10^4 to 9.0x10^6 m/s along a lenght of 2.3 cm. (15) a. How much time does the electron spend in this 2 cm region? b. What is the magnitude of the electron's acceleration?

4. A robotic vehicle is exploring the surface of Mars. The robot, which is represented as a point, has x - and y-coordinates that vary with time: x = (3 − 2t); y = (-t² + 4t³) where x and y are in meters and t is in seconds. a. Find the average velocity of the robot between t = 0s and t = 2s. b. Find the average acceleration of the robot between t = 0s and t = 2s. c. At what time the acceleration of the robot will be zero. a. Vavg= -21 + 14ĵ m/s b. davg = 22ĵ C. m s² 2 t = = = 0.083 s 24

1. The acceleration of a car is given by a(t) = A – Bt + Ct² , where A = 1.0 m/s², B = 0.5 m/s³, C = 2.0 m/s“. The car is at rest at the origin at time t= 0. Find its position and velocity as a function of time. b. Sketch its position, velocity, and acceleration. a.

A jet plane lands with a speed of 145 m/s and can accelerate at a maximum rate of -7.00 m/?2 as it comes to rest. a. From the instant the plane touches the runway, what is the minimum time interval needed before it can come to rest? b. Can this plane land on a small tropical island airport where the runway is 0.9 km long? Why?

a. Find the velocity v(t) and acceleration a(t). b. At what value of t does v=0? c. What is the maximum height?

Consider the following descriptions of the vertical motion of an object subject only to the acceleration due to gravity. Begin with the acceleration equation a(t) = v'(t) = g, where g= - 9.8 m/s. a. Find the velocity of the object for all relevant times. b. Find the position of the object for all relevant times. c. Find the time when the object reaches its highest point. What is the height? d. Find the time when the object strikes the ground. A softball is popped up vertically (from the ground) with a velocity of 25 m/s. а. v(t) b. s(t) = %3D c. The object's highest point is m at time t= S. (Simplify your answers. Round to two decimal places as needed.) d. t= (Simplify your answer. Round to two decimal places as needed.)

A remote-controlled car is moving in a vacant parking lot. The velocity of the car as a function of time is given by v⃗ =[ 5.00m/s − (0.0180m/s3) t2 ] i + [ 2.00m/s + (0.550m/s2) t ] j . a. What is the magnitude of the velocity of the car at t = 8.00 s? b. What is the direction (in degrees counterclockwise from + x-axis) of the velocity of the car at t = 8.00 s? c. What is the magnitude of the acceleration of the car at t = 8.00 s? d. What is the direction (in degrees counterclockwise from + x-axis) of the acceleration of the car at t = 8.00 s?

A rhinoceros is at the origin of coordinates at time t1 = 0. For the time interval from t1 to t2 = 11.0 s, the rhino's average velocity has x-component - 4.20 m/s and y-component 5.10 m/s.  a. At time t2 = 11.0 s what is the x-coordinate of the rhino? b. At time t2 = 11.0 s what is the y-coordinate of the rhino? c. How far is the rhino from the origin?