1.
The units of acceleration are:-
Correct Answer
C. Metres per second squared
Explanation
The units of acceleration are measured in meters per second squared. This unit represents the change in velocity per unit of time. It indicates how much an object's speed changes each second. The term "meters per second squared" specifically refers to the rate at which an object's velocity increases or decreases over time. This unit is commonly used in physics to describe the acceleration of objects in motion.
2.
A cyclist accelerates from rest to 12m/s in 4s. His acceleration is:-
Correct Answer
B. 3m/s2
Explanation
The cyclist accelerates from rest to a final velocity of 12 m/s in a time of 4 seconds. To find the acceleration, we can use the formula: acceleration = (final velocity - initial velocity) / time. In this case, the initial velocity is 0 m/s, the final velocity is 12 m/s, and the time is 4 seconds. Plugging these values into the formula, we get: acceleration = (12 m/s - 0 m/s) / 4 s = 12 m/s / 4 s = 3 m/s^2. Therefore, the correct answer is 3m/s^2.
3.
A car accelerates at 6m/s2 for 4s. If it starts at rest its final speed is:-
Correct Answer
A. 24m/s
Explanation
The car accelerates at a rate of 6m/s2 for 4 seconds. To find the final speed, we can use the formula v = u + at, where v is the final velocity, u is the initial velocity (which is 0 in this case), a is the acceleration, and t is the time. Plugging in the values, we get v = 0 + (6m/s2)(4s) = 24m/s. Therefore, the correct answer is 24m/s.
4.
An aircraft on the runway accelerates at 8m/s2 from rest until it reaches its take-off speed of 60m/s. How long does it take to reach this speed?
Correct Answer
D. 7.5s
Explanation
The aircraft accelerates at a constant rate of 8m/s2 from rest until it reaches its take-off speed of 60m/s. To find the time it takes to reach this speed, we can use the equation of motion: v = u + at, where v is the final velocity, u is the initial velocity, a is the acceleration, and t is the time taken. Rearranging the equation, we have t = (v - u) / a. Plugging in the given values, t = (60 - 0) / 8 = 7.5s. Therefore, it takes 7.5 seconds for the aircraft to reach its take-off speed.
5.
A motor cyclist does an emergency stop when he is travelling at 36m/s. If the motorcycle stops in 3s what is his deceleration?
Correct Answer
E. 12m/s2
Explanation
The deceleration of the motorcyclist can be calculated using the formula: acceleration = change in velocity / time. In this case, the change in velocity is from 36m/s to 0m/s, which is a decrease of 36m/s. The time taken for this change is 3 seconds. Therefore, the deceleration is 36m/s divided by 3s, which equals 12m/s².
6.
A parachutist opens her parachute at an altitude of 1000m when she is travelling at 48m/s. The parachute causes her to decelerate at 4m/s2 for 8s. At what speed does she continue towards the ground?
Correct Answer
C. 12m/s
Explanation
The parachutist opens her parachute when she is traveling at 48m/s. The parachute causes her to decelerate at a rate of 4m/s^2 for 8s. To find the final speed, we can use the equation v = u + at, where v is the final velocity, u is the initial velocity, a is the acceleration, and t is the time. Plugging in the values, we get v = 48 - (4 * 8) = 48 - 32 = 16m/s. Therefore, the correct answer is 16m/s.
7.
To overtake a lorry while travelling at 15m/s a school minibus driver accelerates at 1.5m/s2 for 6s. What is the maximum speed the minibus achieves while overtaking?
Correct Answer
D. 24m/s
Explanation
The minibus driver accelerates at a rate of 1.5m/s² for 6 seconds. Using the equation v = u + at, where v is the final velocity, u is the initial velocity (15m/s), a is the acceleration, and t is the time, we can calculate the final velocity. Plugging in the values, we get v = 15 + (1.5 * 6) = 15 + 9 = 24m/s. Therefore, the maximum speed the minibus achieves while overtaking is 24m/s.
8.
A runner sprints for the line at the end of the 1500m. He is already running at 7.5m/s and he has worked out that he must be travelling at 9.3m/s in less than 9s in order to win the race. What is the smallest acceleration that will allow him to do this?
Correct Answer
A. 0.2m/s2
Explanation
The runner is currently running at a speed of 7.5m/s and needs to increase his speed to 9.3m/s in less than 9 seconds. The smallest acceleration that will allow him to do this can be calculated using the formula: acceleration = (final velocity - initial velocity) / time. Plugging in the values, we get (9.3m/s - 7.5m/s) / 9s = 1.8m/s2. Therefore, the correct answer is 1.8m/s2.
9.
The key difference between velocity and speed is:-
Correct Answer
E. Velocity is used when the direction matters.
Explanation
Velocity is a measure of the speed of an object in a specific direction. Unlike speed, which only considers the magnitude of the object's movement, velocity takes into account both the speed and the direction of the object. This is important in situations where the direction of movement is relevant, such as in physics experiments or when calculating the motion of objects in a particular direction.
10.
A car travelling at a constant speed around a roundabout is accelerating because:-
Correct Answer
D. The car is changing direction
Explanation
The car is changing direction because when it is going around a roundabout, it is constantly turning and following the curvature of the road. Even though the speed of the car may remain constant, the direction in which it is moving is continuously changing, which is considered as acceleration.