Physics-rocket activity.

Rocket activity Original worksheet was produced by Philip Anthony


DEFINITION OF TERMS Maximum height of rocket = H + h Mass of rocket before firing = m_i Mass of rocket after fuel is exhausted = m_f Time from A to C (stopwatch) = t_AC Time from A to B = t_AB Time from B to C = t_BC Average drag from B to C = F_BC Vertical component of AB = x_AB Vertical component of BC = x_BC Distance between observers = D Sight angles of observers = X1 , X2 Speed of rocket at B = v_B
A. Calculating an Estimate of x_AB
• Measure m_i on an electronic balance
• Launch the rocket and measure t_AC , X1⁰ , X2⁰
• Measure m_f on an electronic balance.
The manufacturers quote the impulse and thrust delivered by an “A83” rocket motor as being respectively 2.5 N s and 13.6 N.
• What value does this give for t_AB ? Hint
• What is the mean mass of the rocket as it moves from A to B? Hint
Hide hint (m_f + m_i ) = mean mass If air resistance is (temporarily) ignored what is your estimate of the net force on the rocket as it moves from A to B? The combination of all forces acting on an object is known as the net force. It is the net force that changes an object's state of motion. Hide the hint Hint
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The quantity
Force X time interval
is known as impulse.
impulse = thrust X time
Given the thrust and the impulse of an engine we can calculate the time interval over which the engine produces thrust.

Impulse/thrust = time in seconds.