An identical object is released at height h above the ground from another balloon that is rising at constant speed. Air resistance is negligible. What does not increase for the object released from the rising balloon?
The distance through which it falls
The time taken for it to reach the ground
The speed with which it reaches the ground
Fa. The force of friction is Ff. The weight of the box is Fg and the normal reaction is Fn. Which is the free-body diagram for this situation?
A force acting on a body is proportional to the mass of the body.
The rate of change of momentum of a body is equal to the net external force acting on the body.
The momentum of a body is proportional to the net external force acting on the body.
A force acting on a body is proportional to the acceleration of the body.
5.0 m s–1. After how many seconds will the ball return to its initial position?
What is the efficiency of the system?
m s–2. What is the net force on the cart?
momentum and kinetic energy are both conserved.
momentum is conserved but kinetic energy is not.
kinetic energy is conserved but momentum is not.
neither momentum nor kinetic energy are conserved.
What is the resultant force acting on Y?
Which of the following graphs correctly shows how the acceleration of the particle varies with time?
change in momentum of the body.
rate of change of momentum of the body.
change of kinetic energy of the body.
change of total energy of the body.
m s−1. The upward force acting on the skydiver is approximately
What is W ?
What must be true about the total momentum of the two bodies and the total kinetic energy of the two bodies during this interaction?
Only momentum is conserved.
Only kinetic energy is conserved.
Both momentum and kinetic energy are conserved.
Neither momentum nor kinetic energy are conserved.
m s–1. The graph shows the variation with time t of the force F recorded by the sensor.
What is Fmax?
I. The gain in kinetic energy is less than the loss in gravitational potential energy.
II. The sum of kinetic and gravitational potential energy of the stone is constant.
III. The work done by the force of gravity has the same magnitude as the work done by friction.
I and II only
I and III only
II and III only
I, II and III
The normal reaction acting between the block and the plane is R and the frictional force between the block and the plane is F. The incline is at an angle θ to the horizontal. What is the magnitude of F?
R cos θ
R sin θ
W cos θ
W sin θ
Which of the following is the change in displacement of the object in the first 5.0 seconds?
No physical quantity
2 mv sin θ
2 mv cos θ
only applies if momentum is conserved in the collision.
only applies if energy is conserved in the collision.
only applies if both momentum and energy are conserved in the collision.
What is the magnitude of W compared with the magnitude of F ?
W = F
W > F
A constant net force acts on the body of fixed mass.
A constant net force acts on the body.
The body falls towards the surface of a planet.
The body has an initial velocity of zero.
60 ms−1, she opened her parachute. Which of the following describes her motion after opening her parachute?
She went upwards for a short time, before falling to Earth at a speed of 60 ms−1.
She continued downwards at 60 ms−1, but hit the ground with less force.
She continued to fall but reached a new terminal speed of less than 60 ms−1.
She went upwards for a short time, before falling to Earth at a speed of less than 60 ms−1.
Which of the following expressions is the ratio of
the magnitude of the weight of the block.
the magnitude of the component of weight of the block parallel to the plane.
the magnitude of the component of the normal reaction parallel to the plane.
useful power developed by the engine of the car.
work done by the car against resistive forces.
energy of the car.
rate of change of momentum of the car.
Both forces act for a time t.
What is the rate of change of momentum with time of the object during time t ?
F + f
F – f
(F + f )t1
(F – f )t
What is the momentum of the ball at Q?
The car moves with
acceleration that increases linearly with time.
acceleration that increases non-linearly with time.
/0 to a new length /. The graph shows the variation of force with length for the wire. The energy required to extend the wire from /0 to / is E.
The wire then contracts to half its original extension.
What is the work done by the wire as it contracts?
EK. What is the final kinetic energy when an impulse of 2I acts on an object of mass 2m initially at rest?