Physics Chapter 3

His horizontal and vertical motion are independent. vertical: y = y0 + v0 t + 1/2 a t^2 (a = 9.8 m/s^2) His vertical starting speed is zero. Lets call the top of the cliff y = 0 then y = 0 + 0 - 1/2 9.8 3.2^2 = 50.2 m, so the cliff is 50.2 m high. His horizontal speed remains 2.1 m/s (ignoring friction) So he hits the water 3.2s * 2.1 m/s = 6.72 m out.

A diver running 2.1 m/s dives out horizontally from the edge of a vertical cliff and 3.2 s later reaches the water below. How high was the cliff? How far from its base did the diver hit the water?

At the maximum height, the velocity and acceleration vectors are perpendicular to each other.

A football player kicks a football in a field goal attempt. When the football reaches its maximum height, what is the relationship between the direction of the velocity and acceleration vectors? Assume air resistance is negligible.

down

After the ball has left the bat, and while it is traveling upward (at point P in the figure (Figure 1)), what is the direction of acceleration (Figure 2)? Ignore air resistance.

the cannon should be fired at an angle 45 degrees above the horizon

At what angle, above the horizon, should a cannon be fired in order for the cannon ball to obtain the greatest horizontal range? Assume air resistance is negligible.

Increase the tilt of the yellow track.

Consider the video demonstration that you just watched. Which of the following changes could potentially allow the ball on the straight inclined (yellow) track to win? Ignore air resistance.

four times as far. 2+2

Consider the video you just watched. Suppose we replace the original launcher with one that fires the ball upward at twice the speed. We make no other changes. How far behind the cart will the ball land, compared to the distance in the original experiment?

The horizontal component of the projectile's velocity remains a nonzero constant.

For a projectile launched horizontally, which of the following best describes the horizontal component of a projectile's velocity? Assume air resistance is negligible.

continually increases

For a projectile launched horizontally, which of the following best describes the vertical component of a projectile's velocity? Assume air resistance is negligible.

The horizontal component of a projectile's acceleration is zero.

For general projectile motion, which of the following best describes the horizontal component of a projectile's acceleration? Assume air resistance is negligible.

The horizontal component of a projectile's velocity remains a nonzero constant.

For general projectile motion, which of the following best describes the horizontal component of a projectile's velocity? Assume air resistance is negligible.

The vertical component of a projectile's acceleration remains a nonzero constant.

For general projectile motion, which of the following best describes the vertical component of a projectile's acceleration? Assume air resistance is negligible.

magnitude: V = Vx^2 + Vy^2 V = (5.10)^2 + (-7.40)^2 take square root V = 8.99 units Direction: = tan (-1) -7.40 / 5.10 = ans * 180/pi = 55.4 deg --answer

If Vx = 5.10 units and Vy = -7.40 units, determine the magnitude of V⃗. Determine the direction of V⃗ .

A scalar is specified with a single number, but a vector is specified using both a magnitude and a direction.

In the study of physics, what distinguishes a scalar from a vector?

C= 6.00; angle= 270

Vector A⃗ has a magnitude of 3.00 and is directed parallel to the negative y-axis and vector B⃗ has a magnitude of 3.00 and is directed parallel to the positive y-axis. Determine the magnitude and direction angle (as measured counterclockwise from the positive x-axis) of vector C⃗ , if C⃗ =A⃗ −B⃗ .

5, 240 degrees

Vector A⃗ , which is shown in the figure, has a magnitude of 10 and a direction angle of 60º. What is the magnitude and direction angle (as measured counterclockwise from the positive x-axis) of −A⃗ /2?

Displacement

Which of the following is a vector? - Temperature -Mass -Speed -Displacement -Distance

they are all the same

Which of the three kicks in the figure is in the air for the longest time ? They all reach the same maximum height h. Ignore air resistance.

b) The acceleration of the projectile is positive and decreasing when the projectile is moving upwards, zero at the top, and increasingly negative as the projectile descends e) The velocity at the highest point is zero

Which statements are not valid for a projectile? Take up as positive.

A bullet fired from a rifle begins to fall

as soon as it leaves the barrel

Projectile motion is caused by

the downward force of gravity and an initial forward velocity