Look at the speed-time graph of figure. Find a point where the graph is sloping upwards. Is the parachutist accelerating or decelerating ?

Since the acceleration is continuously increasing with time, the magnitude of the slope will also continuously increase with time. In the beginning the graph is sloping upwards, and the parachutist is accelerating. After the parachute opens, the slope is downward and the parachutist is decelerating.

Look at the speed-time graph of figure. Find a point where the graph is sloping upwards. Which of the two forces acting on the parachutist is greater ?

Since the acceleration is continuously increasing with time, the magnitude of the slope will also continuously increase with time. In the beginning the graph is sloping upwards, and the parachutist is accelerating. After the parachute opens, the slope is downward and the parachutist is decelerating. There are two forces acting on the parachute : (1) The weight of the parachutist and the parachute itself and directed vertically downwards and, (2) The air resistance directed upwards. As the parachute is coming down, the weight of the parachutist is more than the air resistance

Look at the speed-time graph of figure. Find a point where the graph is sloping upwards. Explain the shape of the graph after the parachute has opened.

Since the acceleration is continuously increasing with time, the magnitude of the slope will also continuously increase with time. In the beginning the graph is sloping upwards, and the parachutist is accelerating. After the parachute opens, the slope is downward and the parachutist is decelerating. There are two forces acting on the parachute : (1) The weight of the parachutist and the parachute itself and directed vertically downwards and, (2) The air resistance directed upwards. After opening of the parachute, the speed of the parachute is constantly reduced due to upward force of the air resistance, hence the slope of the speed- time graph is negative

A stone of mass 0 . 20 k g falls with an acceleration of 10 . 0 m s 2 . How big is the force that causes this acceleration ?

Mass = 0 . 2 k g Acceleration = 10 m s 2 Force = Mass × Acceleration Force = 0 . 2 × 10 N Force = 2 N

E M B I B E

Cambridge IGCSE® Physics Coursebook Second Edition>Chapter 3 - Forces and Motion>Questions>Q 3.4

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Upper Secondary: IGCSE

IMPORTANT

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An astronaut has a mass of $90 k g$ .

Calculate her weight on the surface of the Earth.

Important Questions on Forces and Motion

EASY

Upper Secondary: IGCSE

IMPORTANT

Cambridge IGCSE® Physics Coursebook Second Edition>Chapter 3 - Forces and Motion>Questions>Q 3.4

An astronaut has a mass of $90 k g$ .

The astronaut travels to Mars, where gravity is weaker. The acceleration of free fall on the surface of Mars has a value $g = 3.7 m / s^{2}$ . Calculate her weight on Mars.