Thermal Physics Exam Trivia Quiz!

1. Two distance-time graphs and two speed-time graphs are shown. Which graph represents an object that is at rest?

A

B

C

D

From the distance-time graph, we can obtain

a) instantaneous distance traveled from Y-axis

b) Instantaneous speed from the gradient at a certain time

c) Average speed by dividing the Y-axis value with the total time taken

From the speed-time graph, we can obtain

a) instantaneous speed traveled from Y-axis

b) Instantaneous acceleration from gradient at a certain time

c) Total distance traveled from the area under the graph

When an object remains stationary, its velocity =0 m/s and its distance will independent with time

Explanation

From the distance-time graph, we can obtain

a) instantaneous distance traveled from Y-axis

b) Instantaneous speed from the gradient at a certain time

c) Average speed by dividing the Y-axis value with the total time taken

From the speed-time graph, we can obtain

a) instantaneous speed traveled from Y-axis

b) Instantaneous acceleration from gradient at a certain time

c) Total distance traveled from the area under the graph

When an object remains stationary, its velocity =0 m/s and its distance will independent with time

2. The diagram shows the speed-time graph for a car. Which area represents the distance traveled while the car is accelerating?

X

X +Y

Y

Y-X

From the speed-time graph, we can obtain

a) instantaneous speed from Y-axis

b) Instantaneous acceleration from the gradient at a certain time

c) total distance traveled from the area under the graph

When an object traveled under acceleration, its speed-time graph should have a positive gradient. And hence X region is the total distance traveled under acceleration

Explanation

From the speed-time graph, we can obtain

a) instantaneous speed from Y-axis

b) Instantaneous acceleration from the gradient at a certain time

c) total distance traveled from the area under the graph

When an object traveled under acceleration, its speed-time graph should have a positive gradient. And hence X region is the total distance traveled under acceleration

3. An object moves at a constant speed for some time, then begins to accelerate. Which distance-time graph shows this motion?

A

B

C

D

From the distance-time graph, we can obtain

a) instantaneous distance traveled from the Y-axis of the graph

b) instantaneous speed from the gradient of the graph

c) average speed by dividing final Y-axis value with total time taken

As the objects experience a constant speed for some time, the graph should be increased with time at a constant gradient.

After a few seconds, The graph will curve up due to it begins to experience an acceleration.

Explanation

From the distance-time graph, we can obtain

a) instantaneous distance traveled from the Y-axis of the graph

b) instantaneous speed from the gradient of the graph

c) average speed by dividing final Y-axis value with total time taken

As the objects experience a constant speed for some time, the graph should be increased with time at a constant gradient.

After a few seconds, The graph will curve up due to it begins to experience an acceleration.

4. A car travels 100km. The journey takes two hours. The highest speed of the car is 80km/ h, and the lowest speed is 40km/ h. What is the average speed for the journey?

40km/h

50km/h

60km/h

120km/h

Average speed = Total distance travelled / Total time taken

Thus,

Average speed = 100 km/ 2hr

Average speed = 50 km/hr

and hence it is regardless of the maximum and minimum speed during the journey

Explanation

Average speed = Total distance travelled / Total time taken

Thus,

Average speed = 100 km/ 2hr

Average speed = 50 km/hr

and hence it is regardless of the maximum and minimum speed during the journey

5. A car travels along the route PQRST in 30 minutes. What is the average speed of the car?

10km/hr

20km/hr

30km/hr

60km/hr

Average speed

= total distance / total time

=(10 +5 + 5 +10)km / (30 min x 1 hr/60min)

= (30km)/0.5hr

= 60km/hrs

Explanation

Average speed

= total distance / total time

=(10 +5 + 5 +10)km / (30 min x 1 hr/60min)

= (30km)/0.5hr

= 60km/hrs

6. Two runners take part in a race. The graph below shows how the speed of each runner changes with time. What does the graph show about the runners at time t?

Both runners are moving at the same speed.

Runner 1 has zero acceleration.

Runner 1 is overtaking runner 2.

Runner 2 is slowing down.

From the speed-time graph, we can obtain

a) Instantaneous speed from the Y-axis of the graph

b) Distance travel from the area under the graph

c) Instantaneous acceleration from the gradient of the graph

At time t, both graphs intercept with one another, and hence both of them run at the same speed(Since they have the same Y value). Both of the runners experience acceleration as the speed of both graphs increases with time. However, runner one experiences constant acceleration while runner two experiences various acceleration. Runner one will only overtake runner two after time t, not at time t.

Explanation

From the speed-time graph, we can obtain

a) Instantaneous speed from the Y-axis of the graph

b) Distance travel from the area under the graph

c) Instantaneous acceleration from the gradient of the graph

At time t, both graphs intercept with one another, and hence both of them run at the same speed(Since they have the same Y value). Both of the runners experience acceleration as the speed of both graphs increases with time. However, runner one experiences constant acceleration while runner two experiences various acceleration. Runner one will only overtake runner two after time t, not at time t.

7. A train begins a journey from a station and travels 60km in a time of 20 minutes. What is the average speed of the train?

3.0 m/s

5.0 m/s

50 m/s

60 m/s

Average speed equal to total distance multiply by the total time taken.

As 1 min= 60 s and 1 km = 1000 m

Hence, Average speed

= 60 km / 20 mins

=( 60 km x 1000 m/km) / (20 min x 60 s/min)

= 60000 m/ 1200 s = 50 m/s

Explanation

Average speed equal to total distance multiply by the total time taken.

As 1 min= 60 s and 1 km = 1000 m

Hence, Average speed

= 60 km / 20 mins

=( 60 km x 1000 m/km) / (20 min x 60 s/min)

= 60000 m/ 1200 s = 50 m/s

8. A large stone is dropped from a bridge into a river. Air resistance can be ignored. Which row describes the acceleration and the speed of the stone as it falls?

Constant acceleration of stone

Increasing acceleration of stone

Constant speed of stone

Increasing speed of stone

A free-falling object will experience a free-fall acceleration of 9.8m/s.

Gravitational will always the same in free-fall conditions and hence the acceleration should be constant. (ideal assumption)

Meanwhile, as the stone experiences acceleration, it means that the speed of the stone increases with time.

Explanation

A free-falling object will experience a free-fall acceleration of 9.8m/s.

Gravitational will always the same in free-fall conditions and hence the acceleration should be constant. (ideal assumption)

Meanwhile, as the stone experiences acceleration, it means that the speed of the stone increases with time.

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