Physics 1

A key falls from a bridge that is 45 m above the water. It falls directly onto a model boat moving with constant velocity that is 12 m in front of the point of impact when the key is released. What is the speed of the boat?

An object is projected straight upward from the ground level with a velocity of 50 m/s. Ignoring air resistance, it will return to the ground in approximately how many seconds?

A Jogger runs with constant speed $v$ through a forest of pine trees. A pine cone starts to fall from a height $h$ when the jogger is directly below it. How far behind the jogger will the pine cone land?

A ball is thrown downward with a speed of 15 m/s from the roof of a 30 m building. At the same instant a ball is thrown upward with a speed of 15 m/s from ground level. Relative to ground level, at what height do the two balls pass each other?

A swimmer can swim with a velocity of 1.0 m/s in still water. The swimmer wishes to swim directly across a river with a current of 0.50 m/s directed from upstream to downstream. To end up directly across the river the swimmer must head at what angle?

In a rescue attempt, a hovering helicopter drops a life preserver to a swimmer being swept downstream by a river current of a constant velocity v. The helicopter is at a height of 9.8 m. The swimmer is 6.0 m upstream from a point directly under the helicopter when the life preserver is released. It lands 2.0 m in front of the swimmer. How fast is the current flowing? Neglect air resistance.

13.7 m/s

9.8 m/s

6.3 m/s

2.8 m/s

A child tosses a ball directly upward. Its total time in the air is T. Its maximum height is H. What is its height after it has been in the air at time T/4? Neglect air resistance.

H/4

H/3

H/2

2H/3

3H/4

A whiffle ball is tossed straight up, reaches its highest point, and falls back down. Air resistance is not negligible. Which of the following statements are true? i. The balls speed is zero a the highest point ii. The balls acceleration is zero at the highest point. iii. The ball takes a longer time to travel up to the highest point than to fall back down.

i only

ii only

i & ii only

i & iii only

i, ii, and iii

A truck driver travels three-fourths the distance of his run at once velocity, v, and then completes his run at one half his original velocity (1/2)*v. What was the trucker’s average speed for the trip?

0.85 v

0.80 v

0.75 v

0.70 v

0.66 v

On a good dry road, a car with good tires may be able to brake with a constant deceleration of 4.92 m/s$^2$ . How long does such a car initially traveling at 24.6 m/s take to stop? How far does it travel this time?

An airplane traveling at 90 m/s at an elevation of 300 m drops a box of supplies to skiers stranded in a snowstorm.

At what horizontal distance from the skiers should the supplies be dropped?

Find the magnitude of the velocity of the box as it reaches the ground.

A person standing on a cliff throws a stone with a horizontal velocity of 12.0 m/s and the stone hits the ground 45.0 m from the base of the cliff. How high is the cliff?

A bullet was shot perfectly horizontally and was aimed directly at the center of a bulls eye 50 meters away. Suppose it struck 5 cm below the target. How fast was it going when it is fired?

An artillery shell is fired with an initial velocity of 110 m/s at an angle of 30∘above the horizontal. Find:

Its position and velocity after 6 s

The time required to reach its maximum height

The horizontal distance (range)

A plastic ball is thrown with a velocity of 18 m/s stays in the air for 3.0 s.

At what angle with respect to the horizontal was it released?

What was the maximum height achieved by the ball?

Find the range of a gun which fires a shell with muzzle velocity v0at an angle θ.

What is the range (your answer in terms of variables?)

Find the angel of elevation θof a gun that fires a shell with muzzle velocity of 115 m/s and hits a target on the same level but 1200 m distant.

Which angle for θgives the maximum possible range for a projectile. In terms of the remaining variables find the hang time, height, and range.

A stone is thrown off the top of a building from a height of 45.0 m. The stone has a launch of angle of 62.5 degrees and a speed of 31.5 m/s.

How long is the stone in flight?

How far from the base of the building does it travel?

What is its speed just before it hits the ground?

As shown in the figure, two blocks with masses m and M (M>m) are pushed by a force F in both Case I and Case II. The surface is horizontal and frictionless. Let R1 be the force that m exerts on M in Case I and RII be the force that m exerts on M in Case II. Which of the following statements is true?

An Object with mass m and initial velocity v is brought to rest by a constant force F acting for a time t and through a distance d. Possible expressions for the magnitude of the force F are: i. $\frac{mv^2}{2d}$ ii. $\frac{2md}{t^2}$ iii. $\frac{mv}{t}$

ii only

iii only

i and ii only

ii and iii only

i, ii, and iii

A toy car of mass 6 kg moving in a straight path, experiences a net force given by the function F = -3t. At time t=0, the car has a velocity of 4 m/s in the positive direction and is located +8 m from the origin. The car will come instantaneously to rest at time t equal to

2/3 s

sqrt( 4/3 ) s

sqrt( 8/3 ) s

sqrt( 8) s

4 s