Physics Exam

Two point masses m and M are separated by a distance d. if the distance between the masses is increased to 3d, how does the gravitational force between them change?

the force will be one ninth as great

A ball is trhrown vertically upward from the surface of the earth. Consider the following quantities: 1)the speed of the ball 2)the velocity of the ball 3) the acceleration of the ball Which is (are) zero when the ball has reached the maximum height?

1 and 2 Only

A brick is dropped from rest from a height of 4.9m. How long does it take the brick to reach the ground?

1.0s

A 20kg crate is suspended from a fixed beam by two vertical ropes. What is the approximate tension in each rope?

100N

A car, starting from rest, accelerates in a straight-line path at a constant rate of 2.5 m/s^2. How far will the car travel in 12 seconds?

180m

An elevator is moving upward with a speed of 11 m/s. Three seconds later, the elevator is still moving upward, but its speed has been reduced to 5.0 m/s. What is the average acceleration of the elevator during the 3.0s interval?

2.0 m/s^2, downward

A park ranger wanted to measure the height of a tall tree. The ranger stood 9.50 m from the base of the tree; and he observed that his line of sight made and angle of 73.5° above the horizontal as he looked at the top of the tree. What is the height of the tree?

20.6 m

The minimum take off speed for a certain airplane is 75 m/s. What minimum acceleration is required if the plane must leave a runway of length 950 m? Assume the plane starts from rest at one end of the runway.

3.0 m/s^2

A projectile fired from a gun has initial horizontal and vertical components of velocity equal to 30 m/s and 40 m/s, respectivly. What is the speed of the projectile when it is at the highest point in its trajectory?

30m/s

An object is moving along the x axis. The graph shows its position from the starting point as a function of time. Various segments of the graph are identified by the letters A, B, C, and D (https://www.dropbox.com/s/xmx8x1p6nsfk4rt/20170123_181458.jpg?dl=0). What is the velocity of the object at t=7.0s?

-3.0 m/s

An object is moving along the x axis. The graph shows its position from the starting point as a function of time. Various segments of the graph are identified by the letters A, B, C, and D (https://www.dropbox.com/s/xmx8x1p6nsfk4rt/20170123_181458.jpg?dl=0). What is the acceleration of the object at t= 7.0s?

0 m/s^2

A projectile fired from a gun has initial horizontal and vertical components of velocity equal to 30 m/s and 40 m/s, respectivly. Approximently how long it take the projectile to reach the highest point in its trajectory.

4s

a 2400kg satelllite is in a circular orbit around a planet. The satellite travels with a constant speed of 6.67 x 10^3 m/s. The radius of the circular orbit is 8.92x10^6 m. What is the acceleration of the satellite?

5.0 m/s^2

A projectile fired from a gun has initial horizontal and vertical components of velocity equal to 30 m/s and 40 m/s, respectivly. What is the magnitude of the projectile's velocity just before it strikes the ground.

50 m/s

A projectile fired from a gun has initial horizontal and vertical components of velocity equal to 30 m/s and 40 m/s, respectivly. Determine the initial speed of the projectile.

50m/s

A projectile fired from a gun has initial horizontal and vertical components of velocity equal to 30 m/s and 40 m/s, respectivly. At what angle is the projectile fired (measured with respect to the horizontal)?

53°

Neglecting air resistance, what maximum height will be researched by a stone thrown straight up with an initial speed of 35 m/s?

63m

A projectile fired from a gun has initial horizontal and vertical components of velocity equal to 30 m/s and 40 m/s, respectivly. What is the acceleration of the projectile when it reaches it maximum height?

9.8 m/s^2 downward

A tennis ball is thrown at an angle point A. It follows a parabolic trajectory and hits the ground at point D. At the instant shown, the ball is at point B. Point C represents the highest position of the ball above the ground. At which point is the velocity vector changing most rapidly with time?

It is changing at the same rate at all four points.

A football is kicked at an angle respect to the horizontal. Which one of the following statements best describes the accelrration of the football during thia event if air resistance is neglected?

The accelrration is 9.8 m/s^2

A tennis ball is thrown at an angle point A. It follows a parabolic trajectory and hits the ground at point D. At the instant shown, the ball is at point B. Point C represents the highest position of the ball above the ground. Which statement is true concerning the ball when it is at C, the highest point in its trajectory?

The ball's velocity is perpendicular to its acceleration

which force is responsible for holding a car in a friction less banked curve?

The horizontal component of the normal force

A tennis ball is thrown at an angle point A. It follows a parabolic trajectory and hits the ground at point D. At the instant shown, the ball is at point B. Point C represents the highest position of the ball above the ground. While in flight how do the x and y components of the velocity vector of the ball compare at points A and D?

The velocity components have the same magnitudes at both points but the directions of the y components are reversed

A tennis ball is thrown at an angle point A. It follows a parabolic trajectory and hits the ground at point D. At the instant shown, the ball is at point B. Point C represents the highest position of the ball above the ground. While in flight how do the x and y components of the velocity vector of the ball compare at the points B and C?

The x components are the same; the y components at C is zero m/s

A particle travels along a curved path between two points P and Q as shown (https://www.dropbox.com/s/nidtrqoeyg0bk19/20170123_181523.jpg?dl=0). the displacement of the particle does not depend on a) the distance traveled from P to Q b) the direction of Q from P c) the location of Q d) the location of P e) the shortest distance between P and Q

a) is correct

A spaceship is in orbit around the earth at an amplitude of 12,000 miles. Which one of the following statements best explains why the astronauts experience 'weightlessness'? a) the spaceship is in free fall and its floor cannot press upwards on the astronauts b) the force of the earth on the spaceship and the force of the spaceship on the earth cancel because they are equal in magnitude but opposite in direction c) the force of gravity decreases as the inverse square of the distance from the earth's center d) the pull of the earth on the spaceship is canceled by the pull of the other planets e) the centripetal force of the earth on the astronaut in orbit is zero newtons

a) is correct

Starting from rest, a particle confined to move along a straight line is accelerated at a rate of 5.0 m/s^2. Which one of the following statements accurately describes the motion of this particle? a) the speed of the particle increases by 5.0 m/s during each second b) the final speed of the particle will be proportional to the distance that the particle covers c) the particle travels 5.0m during each second d) the particle travels 5.0 m during the first second e) the acceleration of the particle increases by 5.0 m/s^2 during each second?

a) is correct

A rock is thrown vertically upward from the surface of the earth. The rock rises to some maximum height and falls back toward the surface of the earth. Which one of the following statements concerning this situation is true if air resistance is neglected? a)The velocity and acceleraton of the ball always point in the same direction b) as the ball rises, its acceleration vector points upward c) the speed of the ball is negative while the ball falls back toward the earth d) the ball is a freely falling body for the duration of its flight e)The acceleration of the ball is zero when the ball is at its highest point

d) is correct

Which one of the following is not a vector quantity? a) average velocity b) instantaneous velocity c) acceleration d) average speed e) displacement

d) is correct

An object is moving along the x axis. The graph shows its position from the starting point as a function of time. Various segments of the graph are identified by the letters A, B, C, and D (https://www.dropbox.com/s/xmx8x1p6nsfk4rt/20170123_181458.jpg?dl=0). During which interval(s) is the object moving in the negative direction?

during interval B only

a rock is thrown straight upward from the earth's surface. Which one of the following statements concerning the net force acting on the rock at the top of its path is true> a) the net force is greater than the weight of the rock b) the net force is less than the weight of the rock, but greater than zero newtons c) the net force is instantaneously equal to zero newtons d) the net force's direction changes from up to down e) the net force is equal to the weight of the rock

e) is correct

an astronaut orbits the earth in a space capsule whose height above the earth is equal to the earth's radius. How does the mass of the astronaut in the capsule compare to her mass on earth?

her mass is equal to her mass on earth