Physics Review Part 2

An object moving in the +x direction experiences an acceleration of +2.0 m/s2.
This means the object
A) travels 2.0 m in every second.
B) is traveling at 2.0 m/s.
C) is decreasing its velocity by 2.0 m/s every second.
D) is increasing its velocity by 2.0 m/s every second.

Suppose that an object is moving with a constant velocity. Which statement concerning its acceleration must be correct?
A) The acceleration is constantly increasing.
B) The acceleration is constantly decreasing.
C) The acceleration is a constant non-zero value.
D) The acceleration is equal to zero.

When a ball is thrown straight up with no air resistance, the acceleration at its highest point
A) is upward
B) is downward
C) is zero
D) reverses from upward to downward
E) reverses from downward to upward

A 10-kg rock and a 20-kg rock are thrown upward with the same initial speed v0
and experience no significant air resistance. If the 10-kg rock reaches a maximum height h, what maximum height will the 20-kg ball reach?
A) h/4
B) h/2
C) h
D) 2h
E) 4h

From the edge of a roof top you toss a green ball upwards with initial speed v0 and a blue ball downwards with the same initial speed. Air resistance is negligible.
When they reach the ground below
A) the green ball will be moving faster than the blue ball.
B) the blue ball will be moving faster than the green ball.
C) the two balls will have the same speed.

An object is moving with constant non-zero acceleration in the +x direction. The velocity versus time graph of this object is

A) a horizontal straight line.
B) a vertical straight line.
C) a straight line making an angle with the time axis.
D) a parabolic curve.

The slope of a position versus time graph gives
A) the distance traveled.
B) velocity.
C) acceleration.
D) displacement.

If the velocity versus time graph of an object is a straight line making an angle of +30° (counter clockwise) with the time axis, the object is
A) moving with constant non-zero speed.
B) moving with constant non-zero acceleration.
C) at rest.
D) moving with increasing acceleration.

What must be your average speed in order to travel 350 km in 5.15 h?
A) 66.0 km/h
B) 67.0 km/h
C) 68 km/h
D) 69.0 km/h

An airplane travels at 300 mi/h south for 2.00 h and then at 250 mi/h north for 750 miles. What is the average speed for the trip?
A) 260 mi/h
B) 270 mi/h
C) 275 mi/h
D) 280 mi/h

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/s2
B) 1000 m/s2
C) None of the above

The velocity v(t) of a particle as a function of time is given by v(t) = (2.3 m/s) + (4.1 m/s2)t – (6.2 m/s3)t2. What is the average acceleration of the particle between t = 1.0 s and t = 2.0 s (up to two significant figures) ?
A) -13 m/s2
B) -14 m/s2
C) 13 m/s2
D) 15 m/s2 E) None of the above

A car initially traveling at 60 km/h accelerates at a constant rate of 2.0 m/s2. How much time is required for the car to reach a speed of 90 km/h? (Hint: convert km/h to m/s and then use v_f=v_i + a (delta_t))
A) 15 s
B) 30 s
C) 45 s
D) 4.2 s

A jet plane is launched from a catapult on an aircraft carrier. In 2.0 s it reaches a speed of 42 m/s at the end of the catapult. Assuming the acceleration is constant, how far did it travel during those 2.0 s? (Hint: Find the acceleration using initial velocity, final velocity and time and then use 2nd kinematic equation of motion – change in position = (initial velocity x delta_t)+ 1/2 a (delta_t)^2)
A) 16 m
B) 24 m
C) 42 m
D) 84 m

An object is moving in a straight line with constant acceleration. Initially it is traveling at 16 m/s. Three seconds later it is traveling at 10 m/s. How far does it move during this time? (Hint: Find acceleration first it is -2 units and using that
value use 2nd kinematic equation again)
A) 30 m
B) 39 m
C) 48 m
D) 57 m

A car accelerates from 5.0m/s to 21m/s at a constant rate of 3.0m/s2. How far does it travel while accelerating? (Hint: Use a = (v2-v1)/time and find time. and then use the 2nd kinematic equation of motion)
A) 69 m
B) 207 m
C) 41 m
D) 117 m

A stone is thrown with an initial upward velocity of 7.0 m/s and experiences negligible air resistance. If we take upward as the positive direction, what is the
velocity of the stone after 0.50 s? (Hint : a = -g Use fin_vel = init_velocity – g
times time_interval)
A) 2.1 m/s
B) 4.9 m/s
C) -2.1 m/s
D) -4.9 m/s
E) 0.00 m/s

A hammer is thrown upward with a speed of 14 m/s on the surface of planet X
where the acceleration due to gravity is 3.5 m/s2 and there is no atmosphere. What is the speed of the hammer after 8.0 s? (Hint : Use a = -g then Use fin_vel =
init_velocity – g times time_interval)
A) 7.0 m/s
B) 14 m/s
C) 21 m/s
D) 64 m/s

A car is traveling at 26.0 m/s when the driver suddenly applies the brakes, causing the car to slow down with constant acceleration. The car comes to a stop in
a distance of 120 m. How fast was the car moving when it was 60.0 m past the point where the brakes were applied? (Hint: use third kinematic equation of motion
v_fin^2 = v_init^2 – 2 times a times displacement and find a which will be -2.8units and then using that same acceleration use displacement =60 in the same equation and find the speed of the car at 60 m past the initial point).

A) 22.5 m/s
B) 18.4 m/s
C) 15.0 m/s
D) 12.1 m/s
E) 9.20 m/s

A stone is thrown with an initial upward velocity of 7.0 m/s and experiences negligible air resistance. If we take upward as the positive direction, what is the
velocity of the stone after 0.50 s?
A) 2.1 m/s
B) 4.9 m/s
C) -2.1 m/s
D) -4.9 m/s
E) 0.00 m/s

A laser is thrown upward with a speed of 12 m/s on the surface of planet X
where the acceleration due to gravity is 1.5 m/s2 and there is no atmosphere. How long does it take for the laser to reach the maximum height? (Hint : Use a = -g then Use fin_vel = init_velocity – g times time_interval)
A) 8.0 s
B) 11 s
C) 14 s
D) 16 s

A laser is thrown upward with a speed of 12 m/s on the surface of planet X
where the acceleration due to gravity is 1.5 m/s2 and there is no atmosphere. What is the maximum height reached by the laser?
A) 8.0 m
B) 18 m
C) 48 m
D) 144 m

Human reaction time is usually greater than 0.10 s. If your friend holds a ruler between your fingers and releases it without warning, how far can you expect the
ruler to fall before you catch it, assuming negligible air resistance? (USe : displacement starting with zero velocity = 1/2 g time t^2 )
A) At least 3.0 cm
B) At least 4.9 cm
C) At least 6.8 cm
D) At least 9.8 cm

A ball is thrown straight upward from ground level with a speed of 18m/s. How much time passes before the ball strikes the ground if we disregard air
resistance?(USe : final_vel = init_vel – g times t and the required to go up is same as time
required to go down )
A) 3.7 s
B) 1.8 s
C) 1.1 s
D) 0.6 s

An object is thrown upwards with a speed of 16 m/s. How long does it take it
to reach a height of 7.0 m on the way up? Neglect air resistance (so acceleration a = -g). (Use second kinematic equation of motion, g=9.8m/s2 and solve for t)
A) 0.52 s
B) 1.2 s
C) 2.4 s D) 3.1 s
E) 4.2 s

A car is able to stop in a distance d. Assuming the same braking force (and therefore the same acceleration), what distance does this car require to stop when it is traveling twice as fast? (Hint : v_fin^2 = v_init^2 + 2 times a times

displacement : Final velocity is 0 so for the first case we get 0 = v_init^2 +2times a x d ; For the second one velocity is double so we get 0 = (2 times v_init)^2 + 2a times New_d : comparing the two we get new d = 4 times d))
A) d
B) 2d
C) d
D) 4d
E)2 d

Car A is traveling at twice the speed of car B. They both hit the brakes at the same time and decrease their velocities at the same rate. If car B travels a distance
D before stopping, how far does car A travel before stopping?
A) 4D
B) 2D
C) D
D) D/2
E) D/4

If a vector pointing upward has a positive magnitude, a vector pointing
downward has a negative magnitude.
A) True
B) False

Two displacement vectors have magnitudes of 5.0 m and 7.0 m, respectively. If these two vectors are added together, the magnitude of the sum
A) is equal to 2.0 m.
B) could be as small as 2.0 m or as large as 12 m.
C) is equal to 12 m.
D) is equal to 8.6 m.

If a vector A has components Ax > 0, and Ay < 0, then the angle that this vector makes with the positive x-axis must be in the range A) 0° to 90° B) 90° to 180° C) 180° to 270° D) 270° to 360° E) cannot be determined without additional information

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?
A) It is impossible to tell because we do not know their masses.
B) the stone
C) the ball
D) Both are traveling at the same speed.

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
A) be behind the package.
B) be directly over the package.
C) be in front of the package.
D) depend on the speed of the plane when the package was released.

If a satellite moves with constant speed in a perfectly circular orbit around the earth, what is the direction of the acceleration of the satellite?
A) in the forward direction
B) in the backward direction
C) outward away from the earth
D) inward toward the earth
E) The acceleration is zero because the speed is constant.

A velocity vector has components 36 m/s westward and 22 m/s northward. What are the magnitude and direction of this vector?

A player throws a football 50.0 m at 61.0° north of west. What is the westward component of the displacement of the football? ( Hint : 50 cos 61deg) A) 64.7m
B) 55.0 m C) 0.00 m

D) 74.0 m E) 24.2 m

The x and y components of a vector in a horizontal plane are 4.00 m and 3.00 m, respectively. (Hint the angle with x axis : ! and the angle asked is with
respect to poise y-axis so it will be 90 – ! = …)
(a) What is the magnitude of this vector?
(b) What angle does this vector make with the positive +y-axis.

A car travels 20 km west and then 20 km south. What is the magnitude of its
displacement vector?
A) 0 km
B) 20km
C) 28km
D) 40km

A girl throws a rock horizontally, with a velocity of 10 m/s, from a bridge. It falls 20 m to the water below. How far does the rock travel horizontally before striking the water, assuming negligible air resistance? (Hint find time to hit the water first 2s and then velocity times time )
A) 14 m
B) 16 m
C) 20 m
D) 24 m

A boy throws a rock with an initial velocity of 3.13m/s at 30.0° above the horizontal. How long does it take for the rock to reach the maximum height of its
trajectory if air resistance is negligibly small and g = 9.80 m/s2? (Hint : the vertical component of the velocity is 3.13 sin 30 and then use that as the initial vertical
velocity and 0 as the final velocity since the ball stops at the max height. )
A) 0.160 s
B) 0.282 s
C) 0.313 s
D) 0.441 s

An object moving in the +x direction experiences an acceleration of +2.0 m/s2.
This means the object
A) travels 2.0 m in every second.
B) is traveling at 2.0 m/s.
C) is decreasing its velocity by 2.0 m/s every second.
D) is increasing its velocity by 2.0 m/s every second.

A girl throws a rock horizontally with a speed of 12 m/s from a bridge. It falls 2.28 s before hitting the water below. Neglect air resistance.
(a) How high is the bridge from the water below?
(b) How far horizontally does the rock travel before striking the water?

A marble moving 1.48 m/s rolls off the top edge of a 125-cm high table in a room where there is no appreciable air resistance and the acceleration due to
gravity is 9.80 m/s2.
(a) How far from the base of the table will it strike the floor?
(b) How long will it be in the air?

A celebrating student throws a water balloon horizontally from a dormitory window that is 50 m above the ground. It hits the ground at a point 60 m from the building without appreciable air resistance.
(a) What will be the horizontal component of the velocity of the balloon just before it hits the ground?
(b) What will be the magnitude of the vertical velocity of the balloon just before it hits the ground? (Hint : Find time to reach the ground first. Vertical velocity = g
times time_to_reach the ground)

A plane flying horizontally at a speed of 50 m/s and at an elevation of 160 m drops a package, and 2.0 s later it drops a second package. How far apart will the
two packages land on the ground if air resistance is negligible?
A) 100 m
B) 160 m
C) 180 m
D) 320 m

A ball rolls over the edge of a platform with only a horizontal velocity. The height of the platform is 1.6 m and the horizontal range of the ball from the base of the platform is 20 m. What is the horizontal velocity of the ball just before it touches the ground? Neglect air resistance.
A) 35 m/s
B) 9.8 m/s
C) 20 m/s
D) 4.9 m/s
E) 70 m/s

A projectile is fired from ground level with a speed of 150 m/s at an angle 30°
above the horizontal on an airless planet where g = 10.0 m/s2. What is the horizontal component of its velocity after 4.0 s?
A) 150 m/s
B) 35 m/s
C) 130 m/s
D) 75 m/s
E) 38 m/s

A projectile leaves the ground at 150 m/s and reaches a maximum height of 0.57 km. If there was no air resistance, at what angle above the horizontal did it
leave the ground?

An athlete competing in the long jump leaves the ground with a speed of 9.14 m/s at an angle of 35° above the horizontal. How long does the athlete stay in the air, assuming no significant air resistance?
A) 0.50 s
B) 0.88 s
C) 1.1 s
D) 2.5 s
E) 0.54 s

A plane has an eastward heading with an airspeed of 156 m/s. A 20.0 m/s wind is blowing southward at the same time as the plane is flying. The velocity of the
plane relative to the ground is
A) 157 m/s at an angle 7.31° south of east.
B) 157 m/s at an angle 7.31° east of south.
C) 155 m/s at an angle 7.36° south of east.
D) 155 m/s at an angle 7.36° east of south.
E) 157 m/s at an angle 7.36° south of east.

A boat, whose speed in still water is 8.0 m/s, crosses a river with a current of 6.0 m/s. If the boat heads perpendicular to the current, what is the speed of the boat relative to an observer standing on the shore as it crosses the river?
A) 5.3 m/s
B) 6.0 m/s
C) 8.0 m/s
D) 10.0 m/s