Understanding Speed, Distance, and Force

Which of the following is the correct formula to calculate speed?

Answer explanation

The correct formula for speed is s = d/t, where s is speed, d is distance, and t is time. This means speed is calculated by dividing the distance traveled by the time taken.

A car travels 150 km in 3 hours. What is its average speed?

Answer explanation

To find the average speed, divide the total distance by the total time. Here, 150 km ÷ 3 hours = 50 km/h. Thus, the average speed is 50 km/h.

Answer explanation

Work done is calculated using the formula: Work = Force × Distance. Here, Work = 10 N × 5 m = 50 J. Therefore, the correct answer is 50 J.

Which of the following is the SI unit of force?

• Joule

• Newton

• Watt

• Meter

Answer explanation

The SI unit of force is the Newton, named after Sir Isaac Newton. It is defined as the force required to accelerate a one-kilogram mass by one meter per second squared.

Answer explanation

To find the speed, divide the distance by time. Speed = Distance / Time = 60 km / 4 hours = 15 km/h. Thus, the correct answer is 15 km/h.

Answer explanation

To find the distance covered, use the formula: distance = speed × time. Here, speed = 20 m/s and time = 10 s. Thus, distance = 20 m/s × 10 s = 200 m. Therefore, the correct answer is 200 m.

Which equation correctly represents Newton’s Second Law of Motion?

Answer explanation

Newton's Second Law of Motion states that force (F) is equal to mass (m) multiplied by acceleration (a), represented by the equation F = m × a. This shows how force, mass, and acceleration are related.

Answer explanation

Using Newton's second law, F = ma, we can find acceleration (a) by rearranging the formula: a = F/m. Here, F = 25 N and m = 5 kg, so a = 25 N / 5 kg = 5 m/s². Thus, the correct answer is 5 m/s².

Which of the following quantities is a scalar?

• Force

• Distance

• Velocity

• Acceleration

Answer explanation

Distance is a scalar quantity as it only has magnitude and no direction. In contrast, force, velocity, and acceleration are vector quantities, which have both magnitude and direction.

Answer explanation

Acceleration is calculated as the change in speed divided by the time taken. Here, the change in speed is 8 m/s - 4 m/s = 4 m/s. Dividing by the time of 2 seconds gives 4 m/s ÷ 2 s = 2 m/s². Thus, the correct answer is 2 m/s².