Physics

Suppose that a car traveling to the west (-x direction) begins to slow down as it approaches a traffic light. Which statement concerning its acceleration must be correct?

A) its acceleration is positive

A pilot drops a package from a plane flying horizontally at a constant speed. Neglecting air resistance, when the package hits the ground the horizontal location of the plane will

B) be directly over the package

For general projectile motion with no air resistance, the vertical component of a projectile's acceleration

B) remains a non-zero constant

A water rocket can reach a speed of 75 m/s in 0.050 seconds from launch. What is its average acceleration?

A) 1500 m/s squared

If, in the figure, you start from the Bakery, travel to the Café, and then to the Art Gallery (I) what distance you have traveled? (II) what is your displacement?

B) (I) 10.5 km (II) 2.50 km south

A child standing on a bridge throws a rock straight down. The rock leaves the child's hand at time t=0 s. If we take upward as the positive direction , which of the graphs shown below best represents the acceleration of the stone as a function of time?

B) *straight line in the negative part of the graph

A player hits a tennis ball into the air with an initial velocity of 32 m/s at 35 degrees from the horizontal. How fast is the ball moving at the highest point in its trajectory if air resistance is negligible?

B) 26 m/s

An object moves 15.0 m north and then 11.0 m south. Find both the distance it has traveled and the magnitude of its displacement.

B) 26.0 m, 4.0 m

A motorist travels for 3.0 h at 80 km/h and 2.0 h at 100 km/h. What is her average speed for the trip?

B) 88 km/h

Under what condition is average velocity equal to the average of the object's initial and final velocity?

B) The acceleration is constant

An astronaut throws a discus on the moon where the acceleration due to gravity Is 1/6 what is it on earth. He throws the discus with an initial velocity of 20 m/s at an angle of 60 degrees from the horizontal. Neglecting air resistance and the height of the discus at the point of release, what is the range of the discus?

C) 212 m

A racquetball strikes a wall with a speed of 30 m/s and rebounds in the opposite direction with a speed of 26 m/s. The collision takes 20ms. What is the average acceleration of the ball during the collision with the wall?

C) 2800 m/s squared

A runner ran the marathon (approximately 42.0 km) in 2 hours and 57 min. What was the average speed of the runner in m/s?

C) 3.95 m/s

A ball thrown horizontally from a point 24 m above the ground, strikes the ground after traveling horizontally a distance of 18 m. With what speed was it thrown, assuming negligible air resistance?

C) 8.1 m/s

Suppose that an object travels from one point in space to another. Make a comparison between the magnitude of the displacement and the distance traveled by this object.

C) The displacement is either less than or equal to the distance traveled

Which of the following graphs represent an object having zero acceleration?

C) graph a and b

A ball is thrown horizontally from the top of a tower at the same instant that a stone is dropped vertically. Which object is traveling faster when it hits the level ground below if neither of them experiences any air resistance?

C) the ball

James and John drive from an overhang into the lake below. James simply drops straight down from the edge. John takes a running start and jumps with an initial horizontal velocity of 25 m/s. If there is no air resistance, when they reach the lake below

C) the splashdown speed of John is larger than that of James

Three vectors F1, F2, and F3, each of magnitude 70 units, all act on an object as shown in the figure. The magnitude of the resultant vector acting on the object is

D) 0 units

There x component of vector A is 8.7 units, and its y component is -6.5 units. The magnitude of A is closest to

D) 11 units

A stone is thrown horizontally with an initial speed of 10 m/s from the edge of a cliff. A stopwatch measures the stone's trajectory time from the top of the cliff to the bottom to be 4.3 s. What is the height of the cliff if air resistance is negligible small?

D) 91 m

A rock is thrown from the upper edge of a tall cliff at some angle above the horizontal. It reaches its highest point and starts falling down. Which of the following statements about the rock's motion are true just before it hits the ground? (There could be more than one correct choice.)

D) Its horizontal velocity component is the same as it was just as it was launched.

An object moving in the +x direction experiences an acceleration of +2.0 m/s2. This means the object

D) is increasing its velocity by 2.0 m/s every second

For general projectile motion with no air resistance, the horizontal component of a projectile's velocity

D) remains a non-zero constant