A girl stands at rest on a skateboard. The girl and skateboard have a total mass of 50 kg.
She throws a ball of mass 2.0 kg forwards at 10 m/s.
Assume there is no friction.
What is the velocity of the girl and skateboard just after the throw?
0.40 m/s0.40\ \text{m/s}0.40 m/s backwards
0.40 m/s0.40\ \text{m/s}0.40 m/s forwards
2.5 m/s2.5\ \text{m/s}2.5 m/s backwards
5.0 m/s5.0\ \text{m/s}5.0 m/s backwards
50 exam-style questions on OCR GCSE Physics 2.2 Newton’s laws, covering 2.2.1 Interactions between objects, 2.2.2 Force pairs in interactions, 2.2.3 Forces as vectors, 2.2.4 Newton's first law, 2.2.5 Resolving forces with vector diagrams, 2.2.6 Forces acting on an isolated object, 2.2.7 Free body diagrams and resultant force, 2.2.8 Free body diagrams for balanced forces, 2.2.9 Newton's second law, 2.2.10 Inertia and inertial mass, 2.2.11 Momentum in collisions, 2.2.12 Relating force, mass, velocity and acceleration, 2.2.13 Work done by a force, 2.2.14 Work, stored energy and units of energy, 2.2.15 Power as the rate of energy transfer, 2.2.16 Newton's third law, and 2.2.17 Circular motion and changing velocity. Each one has a worked solution and a mark scheme showing where the marks go.