AQA GCSE Physics Newton's laws
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Newton's First Law states that an object will remain at rest or continue moving at a constant velocity, unless it is acted upon by an external resultant force. When there is no resultant force acting on an object, the object is said to be in equilibrium.
Newton's Second Law states that the acceleration of an object is directly proportional to the force acting on it, in the direction of the force, and inversely proportional to the mass of the object. This means that on object will accelerate in the direction of the resultant force being exerted on it, the value of this acceleration depending on the mass of the object.
Newton's Third Law states that when object A exerts a force on object B, then object B exerts an equal and opposite force on object A. This implies that all forces exist in pairs. These two forces must act on different objects, be of the same type of force and act along the same line and for the same time.
A bead is released from the bottom of a vase filled with water. The forces acting on it are upthrust, its weight, and drag. Explain what the relationship between these forces must be for the bead to be rising up the vase at a constant velocity.
A man is pulling a 15 kg box across the floor with a rope that is parallel to the horizontal. If the man applies a force of 150 N and the frictional force exerted by the floor is 20 N, calculate the acceleration of the box.
A ping-pong ball of mass 0.2 kg is released from the bottom of a tube filled with water. Given that it accelerates towards the top at 1.6 m/s² and that the upthrust is 62 N, find the drag acting on the ball. Use g = 9.8 m/s². Provide your answer to 1 decimal place.
A rocket of mass 4 × 10⁶ kg takes off vertically with a thrust of 6.2 × 10⁷ N. Calculate the initial acceleration of the rocket and explain what effect the dropping of the propellers has on the rocket's acceleration. Use g = 9.8 m/s².
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