Physics I Study Guide Ch. 2

An object moves 20 m east in 30 s and then returns to its starting point taking an additional 50 s. If west is chosen as the positive direction, what is the sign associated with the average velocity of the object? a. 0 (no sign) b. - c. + d. Any of the above

a. 0 (no sign)

A vehicle designed to operate on a drag strip accelerates from zero to 30 m/s while undergoing a straight line path displacement of 45 m. What is the vehicle's acceleration if its value may be assumed to be constant? a. 10 m/s2 b. 5.0 m/s2 c. 15 m/s2 d. 2.0 m/s2

a. 10 m/s2

Displacement is which of the following types of quantities? a. Dimensional b. Scalar c. Magnitude d. Vector

d. Vector

Which of the following is not a vector quantity? a. Temperature b. Displacement c. Acceleration d. Velocity

a. Temperature

A strobe photograph of a car moving along a straight road shows the interval between each successive image to be diminishing. If the direction of motion of the car is taken as positive, which of the following are negative? a. the average acceleration of the car b. the average velocity of the car c. all of the above d. the speed of the car

a. the average acceleration of the car

A bird, accelerating from rest at a constant rate, experiences a displacement of 28 m in 11 s. What is its acceleration? a. 0.78 m/s b. 0.46 m/s c. 0.21 m/s d. 0.64 m/s

b. 0.46 m/s

An object moves 20 m east in 30 s and then returns to its starting point taking an additional 50 s. If west is chosen as the positive direction, what is the average speed of the object? a. -0.50 m/s b. 0.50 m/s c. 0.73 m/s d. 0 m/s

b. 0.50 m/s

A cheetah can run at approximately 100 km/hr and a gazelle at 80.0 km/hr. If both animals are running at full speed, with the gazelle 70.0 m ahead, how long before the cheetah catches its prey? a. 10.7 s b. 12.6 s c. 25.2 s d. 6.30 s

b. 12.6 s

An automobile driver puts on the brakes and decelerates from 30.0 m/s to zero in 10.0 s. What distance does the car travel? a. 336 m b. 150 m c. 392 m d. 196 m

b. 150 m

A cheetah can maintain its maximum speed of 100 km/hr for 30.0 seconds. What minimum distance must a gazelle running 80.0 km/hr be ahead of the cheetah to escape? a. 100 m b. 167 m c. 83.0 m d. 70.0 m

b. 167 m

A European sports car dealer claims that his product will accelerate at a constant rate from rest to a speed of 100 km/hr in 8.00 s. What is the speed after the first 5.00 s of acceleration? (Hint: First convert the speed to m/s.) a. 44.4 m/s b. 17.4 m/s c. 34.7 m/s d. 28.7 m/s

b. 17.4 m/s

Jeff throws a ball straight up. For which situation is the vertical velocity zero? a. None of above b. At the top c. On the way up d. On the way back down

b. At the top

In one-dimensional motion where the direction is indicated by a plus or minus sign, the average velocity of an object has which of the following properties? a. It is negative. b. It can be positive, negative, or zero c. It is zero. d. It is positive.

b. It can be positive, negative, or zero

In one-dimensional motion, the average speed of an object that moves from one place to another and then back to its original place has which of the following properties? a. It is zero. b. It is positive. c. It is negative. d. It can be positive, negative, or zero.

b. It is positive.

An object is dropped from a height. Once it is moving, which of the following statements is true, at least at one point? a. Its velocity is less than its acceleration. b. Its velocity is never equal to its acceleration. c. Its velocity is the same as its acceleration. d. Its velocity is more than its acceleration.

b. Its velocity is never equal to its acceleration.

A change in a physical quantity w having initial value wi and final value wf is given by which of the following? a. (wf+wi)/2 b. Wf-Wi c. wi-wf d. None of the above.

b. Wf-Wi

If the displacement of an object is given in SI units by x= -3t+4t2, at t=2s its velocity and acceleration are, respectively: a. negative, negative. b. positive, positive c. negative, positive. d. positive, negative.

b. positive, positive

A strobe photograph shows equally spaced images of a car moving along a straight road. If the time intervals between images is constant, which of the following cannot be positive? a. the speed of the car b. the acceleration of the car c. the average velocity of the car d. the direction of motion of the car

b. the acceleration of the car

An x vs. t graph is drawn for a ball moving in one direction. The graph starts at the origin and at t=5s the velocity of the ball is zero. We can be secure that at t=5s a. the curve is at x=0, t=0 b. the ball has stopped c. the slope of the curve is non-zero. d. the acceleration is constant.

b. the ball has stopped

The slope of the acceleration vs. time curve represents: a. the area under the position vs. time curve. b. the rate of change of acceleration c. the rate of change of displacement. d. the velocity.

b. the rate of change of acceleration

A baseball is released at rest from the top of the Washington Monument. It hits the ground after falling for 6.0 s. What was the height from which the ball was dropped? (g = 9.8 m/s2 and assume air resistance is negligible) a. 1.1 × 102 m b. 2.1 × 102 m c. 1.8 × 102 m d. 1.5 ×102 m

c. 1.8 × 102 m

A baseball is released at rest from the top of the Washington Monument. It hits the ground after falling for 6.0 s. What was the height from which the ball was dropped? (g = 9.8 m/s2 and assume air resistance is negligible) a. 1.5 ×102 m b. 2.1 × 102 m c. 1.8 × 102 m d. 1.1 × 102 m

c. 1.8 × 102 m

Norma releases a bowling ball from rest; it rolls down a ramp with constant acceleration. After half a second it has traveled 0.75 m. How far has it traveled after two seconds? a. 1.2 m b. 9 m c. 12 m d. 6 m

c. 12 m

A rock, released at rest from the top of a tower, hits the ground after 1.5 s. What is the speed of the rock as it hits the ground? (g = 9.8 m/s2 and air resistance is negligible) a. 39 m/s b. 31 m/s c. 15 m/s d. 20 m/s

c. 15 m/s

A ball is pushed with an initial velocity of 4.0 m/s. The ball rolls down a hill with a constant acceleration of 1.6 m/s2. The ball reaches the bottom of the hill in 8.0 s. What is the ball's velocity at the bottom of the hill? a. 12 m/s b. 10 m/s c. 17 m/s d. 16 m/s

c. 17 m/s

Human reaction time is usually about 0.20 s. If your lab partner holds a ruler between your finger and thumb and releases it without warning, how far can you expect the ruler to fall before you catch it? The nearest value is: a. 4.0 cm b. 16 cm c. 20 cm d. 9.8 cm

c. 20 cm

Gwen releases a rock at rest from the top of a 40-m tower. If g = 9.8 m/s2 and air resistance is negligible, what is the speed of the rock as it hits the ground? a. 30 m/s b. 56 m/s c. 28 m/s d. 74 m/s

c. 28 m/s

A European sports car dealer claims that his car will accelerate at a constant rate from rest to 100 km/hr in 8.00 s. If so, what is the acceleration? (Hint: First convert speed to m/s.) a. 11.4 m/s2 b. 17.4 m/s2 c. 3.47 m/s2 d. 6.82 m/s2

c. 3.47 m/s2

A rock is thrown straight up with an initial velocity of 24.5 m/s. What maximum height will the rock reach before starting to fall downward? (Take acceleration due to gravity as 9.80 m/s2.) a. 24.5 m b. 19.6 m c. 30.6 m d. 9.80 m

c. 30.6 m

A truck moves 70 m east, then moves 120 m west, and finally moves east again a distance of 90 m. If east is chosen as the positive direction, what is the truck's resultant displacement? a. -280 m b. 280 m c. 40 m d. -40 m

c. 40 m

Omar throws a rock down with speed 12 m/s from the top of a tower. The rock hits the ground after 2.0 s. What is the height of the tower? (air resistance is negligible) a. 63 m b. 20 m c. 44 m d. 24 m

c. 44 m

A rock is thrown straight down with an initial velocity of 14.5 m/s from a cliff. What is the rock's displacement after 2.0 s? (Acceleration due to gravity is 9.80 m/s2.) a. 64 m b. 55 m c. 49 m d. 28 m

c. 49 m

A bird, accelerating from rest at a constant rate, experiences a displacement of 28 m in 11 s. What is the final velocity after 11 s? a. zero b. 3.2 m/s c. 5.1 m/s d. 1.8 m/s

c. 5.1 m/s

A railroad train travels forward along a straight track at 80.0 m/s for 1,000 m and then travels at 50.0 m/s for the next 1,000 m. What is the average velocity? a. 63.7 m/s b. 65.0 m/s c. 61.5 m/s d. 70.0 m/s

c. 61.5 m/s

The value of an object's acceleration may be characterized in equivalent words by which of the following? a. velocity b. displacement c. rate of change of velocity d. rate of change of displacement

c. rate of change of velocity

A 50-g ball traveling at 25.0 m/s is bounced off a brick wall and rebounds at 22.0 m/s. A high-speed camera records this event. If the ball is in contact with the wall for 3.50 ms, what is the average acceleration of the ball during this time interval? a. 857 m/s2 b. 6,720 m/s2 c. 20 m/s2 d. 13,400 m/s2

d. 13,400 m/s2

A bird, accelerating from rest at a constant rate, experiences a displacement of 28 m in 11 s. What is the average velocity? a. Zero b. 1.7 m/s c. 3.4 m/s d. 2.5 m/s

d. 2.5 m/s

When a drag strip vehicle reaches a velocity of 60 m/s, it begins a negative acceleration by releasing a drag chute and applying its brakes. While reducing its velocity back to zero, its acceleration along a straight line path is a constant -7.5 m/s2. What displacement does it undergo during this deceleration period a. 40 m b. 160 m c. 80 m d. 240 m

d. 240 m

A railroad train travels forward along a straight track at 80.0 m/s for 1,000 m and then travels at 50.0 m/s for the next 1,000 m. What is the average velocity? a. 70.0 m/s b. 63.7 m/s c. 65.0 m/s d. 61.5 m/s

d. 61.5 m/s

Two objects of different mass are released simultaneously from the top of a 20-m tower and fall to the ground. If air resistance is negligible, which statement best applies? a. The greater mass hits the ground first. b. No conclusion can be made with the information given. c. The smaller mass hits the ground first. d. Both objects hit the ground together.

d. Both objects hit the ground together.

A European sports car dealer claims that his product will accelerate at a constant rate from rest to a speed of 100 km/hr in 8.00 s. What distance will the sports car travel during the 8 s acceleration period? (Hint: First convert speed to m/s.) a. 111 m b. 222 m c. 77.7 m d. 55.5 m

a. 111 m

The distance of the Earth from the sun is 93'000,000 miles. If there are 3.15 X 107 s in one year, find the speed of the Earth in its orbit about the sun. a. 18.6 miles/s b. 27.9 miles/s c. 37.2 miles/s d. 9.28 miles/s

a. 18.6 miles/s

A cart is given an initial velocity of 5.0 m/s and experiences a constant acceleration of 2.0 m/s2. What is the magnitude of the cart's displacement during the first 6.0 s of its motion? a. 66 m b. 80 m c. 55 m d. 10 m

a. 66 m