1.
The circuit of a motor racing track is 3 km in length. In a race, a car goes 25 times round the circuit in 30 minutes. What is the average speed of the car?
Correct Answer
C. 150 km/h
Explanation
In order to find the average speed of the car, we need to divide the total distance traveled by the car by the total time taken. The car goes 25 times round the 3 km circuit, which gives us a total distance of 75 km. The race lasts for 30 minutes, which is equal to 0.5 hours. Dividing the total distance of 75 km by the total time of 0.5 hours gives us an average speed of 150 km/h.
2.
An object moves initially with constant speed and then with constant acceleration. Which graph shows this motion?
Correct Answer
B. B
Explanation
Graph B shows the motion of an object that initially moves with constant speed and then with constant acceleration. In this graph, the object starts with a straight line representing constant speed, and then there is a sudden change in slope, indicating the object's acceleration. This change in slope represents the object's increasing velocity over time due to the constant acceleration. Therefore, graph B is the correct representation of the given motion.
3.
A car is moving downhill along a road at a constant speed. Which graph is the speed/ time graph for the car?
Correct Answer
C. C
Explanation
Graph C is the speed/time graph for the car because it shows a constant speed. The slope of the graph is horizontal, indicating that the speed of the car remains constant over time. This is consistent with the statement that the car is moving downhill at a constant speed. Graphs A, B, and D show changes in speed over time, which do not match the given scenario.
4.
The diagram shows a speed-time graph for a body moving with constant acceleration.
Correct Answer
B. Distance
Explanation
The correct answer is "Distance" because the speed-time graph represents the change in speed over time. By calculating the area under the graph, we can determine the distance traveled by the body. The steeper the graph, the greater the acceleration and the larger the area, indicating a greater distance covered. Therefore, the distance is directly related to the acceleration and can be determined from the speed-time graph.
5.
A tunnel has a length of 50 km. A car takes 20 min to travel between the two ends of the tunnel. What is the average speed of the car?
Correct Answer
C. 150 km/h
Explanation
The average speed of the car can be calculated by dividing the total distance traveled by the time taken. In this case, the car traveled a distance of 50 km in 20 minutes. To convert the time to hours, we divide by 60 (20/60 = 1/3). Therefore, the average speed is 50 km divided by 1/3 hours, which equals 150 km/h.
6.
A small steel ball is dropped from a low balcony. Ignoring air resistance, which statement describes its motion?
Correct Answer
A. It falls with constant acceleration
Explanation
The correct answer is "It falls with constant acceleration." This means that the ball is accelerating at a constant rate as it falls due to the force of gravity. The acceleration remains the same throughout the motion, regardless of the ball's speed or position.
7.
The diagram shows the speed-time graph for an object moving at constant speed.
What is the distance in meters travelled by the object in the first 3s?
Correct Answer
A. 18 m
Explanation
The distance travelled by an object can be found by calculating the area under the speed-time graph. In this case, the graph shows a constant speed, which means the object is moving at a consistent rate. The area under the graph for the first 3 seconds is a rectangle with a base of 3 seconds and a height of 6 m/s (since the speed is constant). Therefore, the distance travelled by the object in the first 3 seconds is 3 seconds multiplied by 6 m/s, which equals 18 meters.
8.
A car accelerates from traffic lights. The graph shows how the car’s speed changes with time.
How far does the car travel before it reaches a steady speed?
Correct Answer
D. 100 m
Explanation
To find the distance the car covers during this time, you can use the formula for calculating distance when you know the initial velocity, final velocity, and time:
Distance=1/2×(Initial Velocity + Final Velocity)×Time
In this case, the initial velocity (u) is 0 m/s (as it starts from rest), the final velocity (v) is 20 m/s, and the time (t) is 10 seconds.
So, you can plug these values into the formula:
Distance=1/2×(0m/s+20m/s)×10s = 1/2×20m/s×10s = 100meters
So, the car covers a distance of 100 meters during the 10 seconds.
9.
The graph represents the movement of a body accelerating from rest.
After 5 seconds how far has the body moved?
Correct Answer
A. 50 m
Explanation
The correct answer is 50 m. This can be determined by examining the graph, which represents the movement of a body accelerating from rest. After 5 seconds, the body has moved a distance of 50 m, as indicated by the position on the graph at that time.
10.
A child is standing on the platform of a station, watching the trains.
A train travelling at 30m/s takes 3s to pass the child.
What is the length of the train?
Correct Answer
A. 150 m
Explanation
The length of the train can be calculated by multiplying the speed of the train by the time it takes to pass the child. In this case, the train is traveling at 30 m/s and it takes 3 seconds to pass the child. So, 30 m/s * 3 s = 90 m. Therefore, the length of the train is 90 m.
11.
The graph shows the progress of an athlete in a 100m race.What time was taken to travel 10m from the start?
Correct Answer
B. 2.8 s
Explanation
Based on the graph, the athlete took approximately 2.8 seconds to travel 10 meters from the start. This can be determined by looking at the point on the graph where the distance is 10 meters and finding the corresponding time value, which is closest to 2.8 seconds.
12.
The speed-time graph shown is for a bus travelling between stops. Where on the graph is the acceleration of the bus the greatest?
Correct Answer
B. B
Explanation
The acceleration of the bus is the greatest at point B on the speed-time graph. This can be determined by observing the steepness of the graph at that point. The steeper the graph, the greater the acceleration. At point B, the graph has a sharp increase in speed, indicating a high rate of change in velocity and therefore a high acceleration.